Zachary Palmer

Zachary Palmer

1563433754

What's New in Rails 6?

As most Ruby on Rails fans might be aware, Rails 6 was released this April at RailsConf 2019 and brought a number of eagerly awaited features and changes. Here is a quick recap of the key Rails 6 features you are likely to be using moving forward

For starters, remember that Rails 6 requires Ruby 2.5+ and upgraded databases. So, make sure you have a plan to upgrade your systems accordingly, in case you have not done so already.

Testing in Rails 6

As professional Ruby on Rails developers, we aim to ensure maximum coverage for our code. However, testing becomes a tedious activity when our test cases become “heavy” and we have to wait several minutes, or even hours, just to get the test cases executed.

Parallel Testing

Well, Rails 6 has an answer here. It has added a parallelize method to the ActiveSupport::TestCase which allows you to parallelize the test suite with forked processes.

So, what you need to do to parallelize the processes for your tests is add this to your test_helper.rb:

parallelize(workers: 2)

Alternatively, we can replace our previously used commands for running tests. For example, bin/rails test OR bin/rspec spec can now be replaced by PARALLEL_WORKERS=15 rails test OR PARALLEL_WORKERS=15 rspec spec.

Accordingly, you can change the commands for running the test suites on different CI platforms like Travis, Gitlab, CircleCI, and others.

There are also hooks when each process is created/destroyed, which can be used as follows:

class ActiveSupport::TestCase
  parallelize_setup do |worker|
    # setup databases
  end
  parallelize_teardown do |worker|
    # cleanup databases
  end
  parallelize(workers: :number_of_processors)
end

Note: If you’d like to learn more, you can check out Rails Guides for additional details.

Action Cable Testing

Since we were talking about efficient testing, let’s also understand how Action Cable, one of the most salient features of Rails 5, has improved. Now it is possible to test Action Cable at any level: connections, channels, and broadcasts.

Connection tests aim to check whether a connection’s identifiers get assigned properly or that any improper connection requests are rejected:

class ApplicationCable::ConnectionTest < ActionCable::Connection::TestCase
  test "connects with params" do
 
    connect params: { user_id: 42 }
    OR
    cookies.signed[:user_id] = "42"
    connect
 
    assert_equal connection.user_id, "42"
  end
  test "rejects connection without params" do
    assert_reject_connection { connect }
  end
end

Channel tests can be written to check whether users can subscribe to channels and the channel has a stream:

class ChatChannelTest < ActionCable::Channel::TestCase
  test "subscribes and stream for room" do
    # Simulate a subscription creation by calling `subscribe`
    subscribe room: "15"
    # You can access the Channel object via `subscription` in tests
    assert subscription.confirmed?
    assert_has_stream "chat_15"
  end
end

Broadcasting to channels can be tested like this:

# app/jobs/chat_relay_job.rb
class ChatRelayJob < ApplicationJob
  def perform_later(room, message)
    ChatChannel.broadcast_to room, text: message
  end
end
# test/jobs/chat_relay_job_test.rb
require 'test_helper'
class ChatRelayJobTest < ActiveJob::TestCase
  include ActionCable::TestHelper
  test "broadcast message to room" do
    room = rooms(:all)
    assert_broadcast_on(ChatChannel.broadcasting_for(room), text: "Hi!") do
     ChatRelayJob.perform_now(room, "Hi!")
    end
  end
end

Bulk Insert and Upsert

At some point, we all need to insert multiple records in one go and have found many workarounds when doing so. Well, Rails 6 comes with a new method out of the box—insert_all, similar to update_all.

It won’t fire any callbacks and will execute a single SQL query. There is an additional method upsert_all which allows you to use the upsert operation which is exposed by many modern databases like Postgres. So now you can reduce your insert queries and make your code more optimized. Also, say goodbye to previously used gems like activerecord-import.

A single INSERT SQL query is prepared by these methods, and a single SQL statement is sent to the database, without instantiating the model, or invoking Active Record callbacks and validations. It is also possible to define criteria when a primary key—unique indexes or unique constraints are violated with an option to either skip or run upsert queries.

Some examples are below:

result = Article.insert_all(
  [
    { id: 1,
      title: 'Handling 1M Requests Per Second',
      author: 'John',
      slug: '1m-req-per-second' },
    #...snip...
  ],
  returning: %w[ id title ],
  unique_by: :index_articles_on_title_and_author
)
 
 
result = Article.upsert_all(
  [
    { id: 1, title: 'Handling 1M Requests Per Second', author: 'John', slug: '1m-req-per-second' },
    { id: 1, .... }, # duplicate 'id' here
    { id: 2, .... },
    { id: 3, .... }, # duplicate 'title' and 'author' here
    { id: 4, .... },
    { id: 5, .... }, # duplicate 'slug' here
    { id: 6, .... }
  ]
)

The methods insert, insert! and upsert are wrappers around insert_all, insert_all! and upsert_all, respectively.

Switching Between Multiple Databases

One of the main features many big applications will appreciate is this one: Rails 6 has finally added support for multiple databases for your application, built in and ready to go, out of the box!

Of course, the design choice is still yours, whether you want to break your application into multiple microservices with each having a separate database, or take a monolithic route, or add several read replicas for your application.

However, having the ability to do it in such an easy manner has the potential to save a lot of time on the development front.

So, this is how your new database.yml file will look:

development:
  primary:
    database: my_primary_db
    user: root
  primary_replica:
    database: my_primary_db
    user: ro_user
    replica: true
  animals:
    database: my_animals_db
    user: root
  animals_replica
    database: my_animals_db
    user: ro_user
    replica: true

Here are interesting ways of specifying how to switch to different databases:

class AnimalsModel < ApplicationRecord
  self.abstract_class = true
 
  connects_to database: { writing: :animals_primary, reading: :animals_replica }
end
 
class Dog < AnimalsModel
  # connected to both the animals_primary db for writing and the animals_replica for reading
end

Here is the official GitHub page, which is nicely documented as well. Personally, I am looking forward to having database sharding capabilities in future Rails updates as well.

Action Mailbox

Another interesting React 6 feature is the addition of Action Mailbox, which adds the capability to route incoming emails to the controller like mailboxes for processing in Rails.

Action Mailbox features ingresses for Mailgun, Mandrill, Postmark, and SendGrid. You can also handle inbound emails directly via built-in Exim, Postfix, and Qmail ingresses. Now, you can probably imagine the potential benefits without going into more detail. It may be directly processing mails from a help desk to automating support tickets—Rails 6 allows customers to reply directly through email, and much, much more. The floor is open for you to explore this feature and come up with an approach that is ideal for your application.

Here is a small example to understand how to use Action Mailbox:

COMMENTS_REGEX = /^comment\+(.+)@example\.com/i
 
# app/mailboxes/application_mailbox.rb
class ApplicationMailbox < ActionMailbox::Base
  routing COMMENTS_REGEX => :comments
end
 
# app/mailboxes/comments_mailbox.rb
class CommentsMailbox < ApplicationMailbox
  def process
    user = User.find_by(email: mail.from)
    post_uuid = COMMENTS_REGEX.match(mail.to)[1]
   
    post = Post.find_by(uuid: post_uuid)
    post.comments.create(user: user, content: mail.body)
  end
end

Also, the new way of configuring emails is as follows (taking the example of Sendgrid):

# config/environments/production.rb
config.action_mailbox.ingress = :sendgrid

Use rails credentials:edit to add the password to your application’s encrypted credentials under action_mailbox.ingress_password, where Action Mailbox will automatically find it:

action_mailbox:
  ingress_password: …

Configure the SendGrid Inbound Parse to forward inbound emails to /rails/action_mailbox/sendgrid/inbound_emails with the username actionmailbox and the password you previously generated. If your application lives at <a href="https://example.com" target="_blank">https://example.com</a>, you would configure SendGrid with the following URL:

https://actionmailbox:PASSWORD@example.com/rails/action_mailbox/sendgrid/i 

Zeitwerk

Zeitwerk is the new code loader for Ruby. Given a conventional file structure, Zeitwerk loads your project’s classes and modules on demand, meaning you don’t need to write require calls for your own files. To enable it in Rails 6, you can do the following:

config.autoloader = :zeitwerk

You can read more about Zeitwerk here.

Optimizer Hints

You are concerned that some of your queries are taking too long to execute? Well, now you have a way to define time-outs for your queries, too.

The following statement will raise an StatementTimeout exception if the query takes longer than normal to execute:

User.optimizer_hints("MAX_EXECUTION_TIME(5000)").all

It is supported by MySQL and you’ll have to explore if your database supports it.

Truncate Database

What about seeding data? The following statement will truncate all your database tables and you can then proceed to seeding your data:

rails db:truncate_all

No more deleting your databases to seed. You will probably agree this is an elegant and quick solution.

Action Text

Perhaps another notable feature for many applications that play with WYSIWYG editors is the addition of support for Trix editor natively into Rails 6 applications. This will certainly be a good upgrade/addition for many projects.

Most WYSIWYG HTML editors are enormous in scope—each browser’s implementation has its own set of bugs and quirks, and JavaScript developers are left to resolve the inconsistencies. Trix sidesteps these inconsistencies by treating contenteditable as an I/O device: When input makes its way to the editor, Trix converts that input into an editing operation on its internal document model, then re-renders that document back into the editor. This gives Trix complete control over what happens after every keystroke.

Installation:

rails action_text:install
 
# app/models/message.rb
class Message < ApplicationRecord
  has_rich_text :content
end

You can explore Action Text in further detail in the official documentation, here.

Security

No serious upgrade is complete without a few security enhancements. Rails 6 doesn’t disappoint on the security front, either. The first notable security upgrade is the addition of support for Host Authorization.

Host Authorization is a new middleware that guards against DNS rebinding attacks by explicitly permitting the hosts a request can be sent to. What this means is that you can define the hosts that can access your applications.

Another security upgrade is meant to thwart attacks that attempt to copy the signed/encrypted value of a cookie and use it as the value of another cookie. It does so by stashing the cookie name in the purpose field which is then signed/encrypted along with the cookie value. Then, on the server-side read, we verify the cookie names and discard any attacked cookies. Enable action_dispatch.use_cookies_with_metadata to use this feature, which writes cookies with the new purpose and expiry metadata embedded.

Webpack as the Default Bundler

As is the de facto standard with many modern JavaScript frameworks for front-end development, Rails 6 has added Webpack as the default JavaScript bundler through webpacker gem, replacing the Rails Asset pipeline. This is a relatively straightforward addition, and we won’t go into much detail. Suffice to say that Webpack will bring some relief to overworked front-end developers.

Preventing Race Conditions

Rails 6 has a new method which is used to prevent SELECT/INSERT race conditions in our code (I am sure many readers have had the misfortune of encountering race conditions as they scale their project). Here is the GitHub thread in case you need additional info.

The underlying table must have the relevant columns defined with unique constraints. While we avoid the race condition between SELECT → INSERT from #find_or_create_by, we actually have another race condition between INSERT → SELECT, which can be triggered if a DELETE between those two statements is run by another client. But, for most applications, that’s a condition we’re significantly less likely to hit.

Credentials in Rails 6

Since the days of Rails 5.2, credentials have been named a new “Rails way” to deal with sensitive information with a promise to get rid of infamous .env files once and for all. With credentials, encrypted keys for third-party services can be checked directly into the source control.

Until now, however, Rails used the same encrypted file for all environments, which made dealing with different keys in development and production a little tricky, especially when dealing with big projects and legacy code.

In Rails 6, this is finally solved with support for per-environment credentials. Again, further details can be explored on the official GitHub thread.

#ruby-on-rails #ruby #web-development

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ループを使用して、Rustのデータを反復処理します

このモジュールでは、Rustでハッシュマップ複合データ型を操作する方法について説明します。ハッシュマップのようなコレクション内のデータを反復処理するループ式を実装する方法を学びます。演習として、要求された注文をループし、条件をテストし、さまざまなタイプのデータを処理することによって車を作成するRustプログラムを作成します。

さび遊び場

錆遊び場は錆コンパイラにブラウザインタフェースです。言語をローカルにインストールする前、またはコンパイラが利用できない場合は、Playgroundを使用してRustコードの記述を試すことができます。このコース全体を通して、サンプルコードと演習へのPlaygroundリンクを提供します。現時点でRustツールチェーンを使用できない場合でも、コードを操作できます。

Rust Playgroundで実行されるすべてのコードは、ローカルの開発環境でコンパイルして実行することもできます。コンピューターからRustコンパイラーと対話することを躊躇しないでください。Rust Playgroundの詳細については、What isRust?をご覧ください。モジュール。

学習目標

このモジュールでは、次のことを行います。

  • Rustのハッシュマップデータ型、およびキーと値にアクセスする方法を確認してください
  • ループ式を使用してRustプログラムのデータを反復処理する方法を探る
  • Rustプログラムを作成、コンパイル、実行して、ループを使用してハッシュマップデータを反復処理します

Rustのもう1つの一般的なコレクションの種類は、ハッシュマップです。このHashMap<K, V>型は、各キーKをその値にマッピングすることによってデータを格納しますV。ベクトル内のデータは整数インデックスを使用してアクセスされますが、ハッシュマップ内のデータはキーを使用してアクセスされます。

ハッシュマップタイプは、オブジェクト、ハッシュテーブル、辞書などのデータ項目の多くのプログラミング言語で使用されます。

ベクトルのように、ハッシュマップは拡張可能です。データはヒープに格納され、ハッシュマップアイテムへのアクセスは実行時にチェックされます。

ハッシュマップを定義する

次の例では、書評を追跡するためのハッシュマップを定義しています。ハッシュマップキーは本の名前であり、値は読者のレビューです。

use std::collections::HashMap;
let mut reviews: HashMap<String, String> = HashMap::new();

reviews.insert(String::from("Ancient Roman History"), String::from("Very accurate."));
reviews.insert(String::from("Cooking with Rhubarb"), String::from("Sweet recipes."));
reviews.insert(String::from("Programming in Rust"), String::from("Great examples."));

このコードをさらに詳しく調べてみましょう。最初の行に、新しいタイプの構文が表示されます。

use std::collections::HashMap;

このuseコマンドは、Rust標準ライブラリの一部HashMapからの定義をcollectionsプログラムのスコープに取り込みます。この構文は、他のプログラミング言語がインポートと呼ぶものと似ています。

HashMap::newメソッドを使用して空のハッシュマップを作成します。reviews必要に応じてキーと値を追加または削除できるように、変数を可変として宣言します。この例では、ハッシュマップのキーと値の両方がStringタイプを使用しています。

let mut reviews: HashMap<String, String> = HashMap::new();

キーと値のペアを追加します

このinsert(<key>, <value>)メソッドを使用して、ハッシュマップに要素を追加します。コードでは、構文は<hash_map_name>.insert()次のとおりです。

reviews.insert(String::from("Ancient Roman History"), String::from("Very accurate."));

キー値を取得する

ハッシュマップにデータを追加した後、get(<key>)メソッドを使用してキーの特定の値を取得できます。

// Look for a specific review
let book: &str = "Programming in Rust";
println!("\nReview for \'{}\': {:?}", book, reviews.get(book));

出力は次のとおりです。

Review for 'Programming in Rust': Some("Great examples.")

ノート

出力には、書評が単なる「すばらしい例」ではなく「Some( "すばらしい例。")」として表示されていることに注意してください。getメソッドはOption<&Value>型を返すため、Rustはメソッド呼び出しの結果を「Some()」表記でラップします。

キーと値のペアを削除します

この.remove()メソッドを使用して、ハッシュマップからエントリを削除できます。get無効なハッシュマップキーに対してメソッドを使用すると、getメソッドは「なし」を返します。

// Remove book review
let obsolete: &str = "Ancient Roman History";
println!("\n'{}\' removed.", obsolete);
reviews.remove(obsolete);

// Confirm book review removed
println!("\nReview for \'{}\': {:?}", obsolete, reviews.get(obsolete));

出力は次のとおりです。

'Ancient Roman History' removed.
Review for 'Ancient Roman History': None

このコードを試して、このRustPlaygroundでハッシュマップを操作できます。

演習:ハッシュマップを使用して注文を追跡する
この演習では、ハッシュマップを使用するように自動車工場のプログラムを変更します。

ハッシュマップキーと値のペアを使用して、車の注文に関する詳細を追跡し、出力を表示します。繰り返しになりますが、あなたの課題は、サンプルコードを完成させてコンパイルして実行することです。

この演習のサンプルコードで作業するには、次の2つのオプションがあります。

  • コードをコピーして、ローカル開発環境で編集します。
  • 準備されたRustPlaygroundでコードを開きます。

ノート

サンプルコードで、todo!マクロを探します。このマクロは、完了するか更新する必要があるコードを示します。

現在のプログラムをロードする

最初のステップは、既存のプログラムコードを取得することです。

  1. 編集のために既存のプログラムコードを開きます。コードは、データ型宣言、および定義のため含みcar_qualitycar_factoryおよびmain機能を。

次のコードをコピーしてローカル開発環境で編集する
か、この準備されたRustPlaygroundでコードを開きます。

#[derive(PartialEq, Debug)]
struct Car { color: String, motor: Transmission, roof: bool, age: (Age, u32) }

#[derive(PartialEq, Debug)]
enum Transmission { Manual, SemiAuto, Automatic }

#[derive(PartialEq, Debug)]
enum Age { New, Used }

// Get the car quality by testing the value of the input argument
// - miles (u32)
// Return tuple with car age ("New" or "Used") and mileage
fn car_quality (miles: u32) -> (Age, u32) {

    // Check if car has accumulated miles
    // Return tuple early for Used car
    if miles > 0 {
        return (Age::Used, miles);
    }

    // Return tuple for New car, no need for "return" keyword or semicolon
    (Age::New, miles)
}

// Build "Car" using input arguments
fn car_factory(order: i32, miles: u32) -> Car {
    let colors = ["Blue", "Green", "Red", "Silver"];

    // Prevent panic: Check color index for colors array, reset as needed
    // Valid color = 1, 2, 3, or 4
    // If color > 4, reduce color to valid index
    let mut color = order as usize;
    if color > 4 {        
        // color = 5 --> index 1, 6 --> 2, 7 --> 3, 8 --> 4
        color = color - 4;
    }

    // Add variety to orders for motor type and roof type
    let mut motor = Transmission::Manual;
    let mut roof = true;
    if order % 3 == 0 {          // 3, 6, 9
        motor = Transmission::Automatic;
    } else if order % 2 == 0 {   // 2, 4, 8, 10
        motor = Transmission::SemiAuto;
        roof = false;
    }                            // 1, 5, 7, 11

    // Return requested "Car"
    Car {
        color: String::from(colors[(color-1) as usize]),
        motor: motor,
        roof: roof,
        age: car_quality(miles)
    }
}

fn main() {
    // Initialize counter variable
    let mut order = 1;
    // Declare a car as mutable "Car" struct
    let mut car: Car;

    // Order 6 cars, increment "order" for each request
    // Car order #1: Used, Hard top
    car = car_factory(order, 1000);
    println!("{}: {:?}, Hard top = {}, {:?}, {}, {} miles", order, car.age.0, car.roof, car.motor, car.color, car.age.1);

    // Car order #2: Used, Convertible
    order = order + 1;
    car = car_factory(order, 2000);
    println!("{}: {:?}, Hard top = {}, {:?}, {}, {} miles", order, car.age.0, car.roof, car.motor, car.color, car.age.1);    

    // Car order #3: New, Hard top
    order = order + 1;
    car = car_factory(order, 0);
    println!("{}: {:?}, Hard top = {}, {:?}, {}, {} miles", order, car.age.0, car.roof, car.motor, car.color, car.age.1);

    // Car order #4: New, Convertible
    order = order + 1;
    car = car_factory(order, 0);
    println!("{}: {:?}, Hard top = {}, {:?}, {}, {} miles", order, car.age.0, car.roof, car.motor, car.color, car.age.1);

    // Car order #5: Used, Hard top
    order = order + 1;
    car = car_factory(order, 3000);
    println!("{}: {:?}, Hard top = {}, {:?}, {}, {} miles", order, car.age.0, car.roof, car.motor, car.color, car.age.1);

    // Car order #6: Used, Hard top
    order = order + 1;
    car = car_factory(order, 4000);
    println!("{}: {:?}, Hard top = {}, {:?}, {}, {} miles", order, car.age.0, car.roof, car.motor, car.color, car.age.1);
}

2. プログラムをビルドします。次のセクションに進む前に、コードがコンパイルされて実行されることを確認してください。

次の出力が表示されます。

1: Used, Hard top = true, Manual, Blue, 1000 miles
2: Used, Hard top = false, SemiAuto, Green, 2000 miles
3: New, Hard top = true, Automatic, Red, 0 miles
4: New, Hard top = false, SemiAuto, Silver, 0 miles
5: Used, Hard top = true, Manual, Blue, 3000 miles
6: Used, Hard top = true, Automatic, Green, 4000 miles

注文の詳細を追跡するためのハッシュマップを追加する

現在のプログラムは、各車の注文を処理し、各注文が完了した後に要約を印刷します。car_factory関数を呼び出すたびにCar、注文の詳細を含む構造体が返され、注文が実行されます。結果はcar変数に格納されます。

お気づきかもしれませんが、このプログラムにはいくつかの重要な機能がありません。すべての注文を追跡しているわけではありません。car変数は、現在の注文の詳細のみを保持しています。関数carの結果で変数が更新されるたびcar_factoryに、前の順序の詳細が上書きされます。

ファイリングシステムのようにすべての注文を追跡するために、プログラムを更新する必要があります。この目的のために、<K、V>ペアでハッシュマップを定義します。ハッシュマップキーは、車の注文番号に対応します。ハッシュマップ値は、Car構造体で定義されているそれぞれの注文の詳細になります。

  1. ハッシュマップを定義するには、main関数の先頭、最初の中括弧の直後に次のコードを追加します{
// Initialize a hash map for the car orders
    // - Key: Car order number, i32
    // - Value: Car order details, Car struct
    use std::collections::HashMap;
    let mut orders: HashMap<i32, Car> = HashMap;

2. ordersハッシュマップを作成するステートメントの構文の問題を修正します。

ヒント

ハッシュマップを最初から作成しているので、おそらくこのnew()メソッドを使用することをお勧めします。

3. プログラムをビルドします。次のセクションに進む前に、コードがコンパイルされていることを確認してください。コンパイラからの警告メッセージは無視してかまいません。

ハッシュマップに値を追加する

次のステップは、履行された各自動車注文をハッシュマップに追加することです。

このmain関数では、car_factory車の注文ごとに関数を呼び出します。注文が履行された後、println!マクロを呼び出して、car変数に格納されている注文の詳細を表示します。

// Car order #1: Used, Hard top
    car = car_factory(order, 1000);
    println!("{}: {}, Hard top = {}, {:?}, {}, {} miles", order, car.age.0, car.roof, car.motor, car.color, car.age.1);

    ...

    // Car order #6: Used, Hard top
    order = order + 1;
    car = car_factory(order, 4000);
    println!("{}: {}, Hard top = {}, {:?}, {}, {} miles", order, car.age.0, car.roof, car.motor, car.color, car.age.1);

新しいハッシュマップで機能するように、これらのコードステートメントを修正します。

  • car_factory関数の呼び出しは保持します。返された各Car構造体は、ハッシュマップの<K、V>ペアの一部として格納されます。
  • println!マクロの呼び出しを更新して、ハッシュマップに保存されている注文の詳細を表示します。
  1. main関数で、関数の呼び出しcar_factoryとそれに伴うprintln!マクロの呼び出しを見つけます。
// Car order #1: Used, Hard top
    car = car_factory(order, 1000);
    println!("{}: {}, Hard top = {}, {:?}, {}, {} miles", order, car.age.0, car.roof, car.motor, car.color, car.age.1);

    ...

    // Car order #6: Used, Hard top
    order = order + 1;
    car = car_factory(order, 4000);
    println!("{}: {}, Hard top = {}, {:?}, {}, {} miles", order, car.age.0, car.roof, car.motor, car.color, car.age.1);

2. すべての自動車注文のステートメントの完全なセットを次の改訂されたコードに置き換えます。

// Car order #1: Used, Hard top
    car = car_factory(order, 1000);
    orders(order, car);
    println!("Car order {}: {:?}", order, orders.get(&order));

    // Car order #2: Used, Convertible
    order = order + 1;
    car = car_factory(order, 2000);
    orders(order, car);
    println!("Car order {}: {:?}", order, orders.get(&order));

    // Car order #3: New, Hard top
    order = order + 1;
    car = car_factory(order, 0);
    orders(order, car);
    println!("Car order {}: {:?}", order, orders.get(&order));

    // Car order #4: New, Convertible
    order = order + 1;
    car = car_factory(order, 0);
    orders(order, car);
    println!("Car order {}: {:?}", order, orders.get(&order));

    // Car order #5: Used, Hard top
    order = order + 1;
    car = car_factory(order, 3000);
    orders(order, car);
    println!("Car order {}: {:?}", order, orders.get(&order));

    // Car order #6: Used, Hard top
    order = order + 1;
    car = car_factory(order, 4000);
    orders(order, car);
    println!("Car order {}: {:?}", order, orders.get(&order));

3. 今すぐプログラムをビルドしようとすると、コンパイルエラーが表示されます。<K、V>ペアをordersハッシュマップに追加するステートメントに構文上の問題があります。問題がありますか?先に進んで、ハッシュマップに順序を追加する各ステートメントの問題を修正してください。

ヒント

ordersハッシュマップに直接値を割り当てることはできません。挿入を行うにはメソッドを使用する必要があります。

プログラムを実行する

プログラムが正常にビルドされると、次の出力が表示されます。

Car order 1: Some(Car { color: "Blue", motor: Manual, roof: true, age: ("Used", 1000) })
Car order 2: Some(Car { color: "Green", motor: SemiAuto, roof: false, age: ("Used", 2000) })
Car order 3: Some(Car { color: "Red", motor: Automatic, roof: true, age: ("New", 0) })
Car order 4: Some(Car { color: "Silver", motor: SemiAuto, roof: false, age: ("New", 0) })
Car order 5: Some(Car { color: "Blue", motor: Manual, roof: true, age: ("Used", 3000) })
Car order 6: Some(Car { color: "Green", motor: Automatic, roof: true, age: ("Used", 4000) })

改訂されたコードの出力が異なることに注意してください。println!マクロディスプレイの内容Car各値を示すことによって、構造体と対応するフィールド名。

次の演習では、ループ式を使用してコードの冗長性を減らします。

for、while、およびloop式を使用します


多くの場合、プログラムには、その場で繰り返す必要のあるコードのブロックがあります。ループ式を使用して、繰り返しの実行方法をプログラムに指示できます。電話帳のすべてのエントリを印刷するには、ループ式を使用して、最初のエントリから最後のエントリまで印刷する方法をプログラムに指示できます。

Rustは、プログラムにコードのブロックを繰り返させるための3つのループ式を提供します。

  • loop:手動停止が発生しない限り、繰り返します。
  • while:条件が真のままで繰り返します。
  • for:コレクション内のすべての値に対して繰り返します。

この単元では、これらの各ループ式を見ていきます。

ループし続けるだけ

loop式は、無限ループを作成します。このキーワードを使用すると、式の本文でアクションを継続的に繰り返すことができます。ループを停止させるための直接アクションを実行するまで、アクションが繰り返されます。

次の例では、「We loopforever!」というテキストを出力します。そしてそれはそれ自体で止まりません。println!アクションは繰り返し続けます。

loop {
    println!("We loop forever!");
}

loop式を使用する場合、ループを停止する唯一の方法は、プログラマーとして直接介入する場合です。特定のコードを追加してループを停止したり、Ctrl + Cなどのキーボード命令を入力してプログラムの実行を停止したりできます。

loop式を停止する最も一般的な方法は、breakキーワードを使用してブレークポイントを設定することです。

loop {
    // Keep printing, printing, printing...
    println!("We loop forever!");
    // On the other hand, maybe we should stop!
    break;                            
}

プログラムがbreakキーワードを検出すると、loop式の本体でアクションの実行を停止し、次のコードステートメントに進みます。

breakキーワードは、特別な機能を明らかにするloop表現を。breakキーワードを使用すると、式本体でのアクションの繰り返しを停止することも、ブレークポイントで値を返すこともできます。

次の例はbreakloop式でキーワードを使用して値も返す方法を示しています。

let mut counter = 1;
// stop_loop is set when loop stops
let stop_loop = loop {
    counter *= 2;
    if counter > 100 {
        // Stop loop, return counter value
        break counter;
    }
};
// Loop should break when counter = 128
println!("Break the loop at counter = {}.", stop_loop);

出力は次のとおりです。

Break the loop at counter = 128.

私たちのloop表現の本体は、これらの連続したアクションを実行します。

  1. stop_loop変数を宣言します。
  2. 変数値をloop式の結果にバインドするようにプログラムに指示します。
  3. ループを開始します。loop式の本体でアクションを実行します:
    ループ本体
    1. counter値を現在の値の2倍にインクリメントします。
    2. counter値を確認してください。
    3. もしcounter値が100以上です。

ループから抜け出し、counter値を返します。

4. もしcounter値が100以上ではありません。

ループ本体でアクションを繰り返します。

5. stop_loop値を式のcounter結果である値に設定しますloop

loop式本体は、複数のブレークポイントを持つことができます。式に複数のブレークポイントがある場合、すべてのブレークポイントは同じタイプの値を返す必要があります。すべての値は、整数型、文字列型、ブール型などである必要があります。ブレークポイントが明示的に値を返さない場合、プログラムは式の結果を空のタプルとして解釈します()

しばらくループする

whileループは、条件式を使用しています。条件式が真である限り、ループが繰り返されます。このキーワードを使用すると、条件式がfalseになるまで、式本体のアクションを実行できます。

whileループは、ブール条件式を評価することから始まります。条件式がと評価されるtrueと、本体のアクションが実行されます。アクションが完了すると、制御は条件式に戻ります。条件式がと評価されるfalseと、while式は停止します。

次の例では、「しばらくループします...」というテキストを出力します。ループを繰り返すたびに、「カウントが5未満である」という条件がテストされます。条件が真のままである間、式本体のアクションが実行されます。条件が真でなくなった後、whileループは停止し、プログラムは次のコードステートメントに進みます。

while counter < 5 {
    println!("We loop a while...");
    counter = counter + 1;
}

これらの値のループ

forループは、項目のコレクションを処理するためにイテレータを使用しています。ループは、コレクション内の各アイテムの式本体のアクションを繰り返します。このタイプのループの繰り返しは、反復と呼ばれます。すべての反復が完了すると、ループは停止します。

Rustでは、配列、ベクトル、ハッシュマップなど、任意のコレクションタイプを反復処理できます。Rustはイテレータを使用して、コレクション内の各アイテムを最初から最後まで移動します

forループはイテレータとして一時変数を使用しています。変数はループ式の開始時に暗黙的に宣言され、現在の値は反復ごとに設定されます。

次のコードでは、コレクションはbig_birds配列であり、イテレーターの名前はbirdです。

let big_birds = ["ostrich", "peacock", "stork"];
for bird in big_birds

iter()メソッドを使用して、コレクション内のアイテムにアクセスします。for式は結果にイテレータの現在の値をバインドするiter()方法。式本体では、イテレータ値を操作できます。

let big_birds = ["ostrich", "peacock", "stork"];
for bird in big_birds.iter() {
    println!("The {} is a big bird.", bird);
}

出力は次のとおりです。

The ostrich is a big bird.
The peacock is a big bird.
The stork is a big bird.

イテレータを作成するもう1つの簡単な方法は、範囲表記を使用することですa..b。イテレータはa値から始まりb、1ステップずつ続きますが、値を使用しませんb

for number in 0..5 {
    println!("{}", number * 2);
}

このコードは、0、1、2、3、および4の数値をnumber繰り返し処理します。ループの繰り返しごとに、値を変数にバインドします。

出力は次のとおりです。

0
2
4
6
8

このコードを実行して、このRustPlaygroundでループを探索できます。

演習:ループを使用してデータを反復処理する


この演習では、自動車工場のプログラムを変更して、ループを使用して自動車の注文を反復処理します。

main関数を更新して、注文の完全なセットを処理するためのループ式を追加します。ループ構造は、コードの冗長性を減らすのに役立ちます。コードを簡素化することで、注文量を簡単に増やすことができます。

このcar_factory関数では、範囲外の値での実行時のパニックを回避するために、別のループを追加します。

課題は、サンプルコードを完成させて、コンパイルして実行することです。

この演習のサンプルコードで作業するには、次の2つのオプションがあります。

  • コードをコピーして、ローカル開発環境で編集します。
  • 準備されたRustPlaygroundでコードを開きます。

ノート

サンプルコードで、todo!マクロを探します。このマクロは、完了するか更新する必要があるコードを示します。

プログラムをロードする

前回の演習でプログラムコードを閉じた場合は、この準備されたRustPlaygroundでコードを再度開くことができます。

必ずプログラムを再構築し、コンパイラエラーなしで実行されることを確認してください。

ループ式でアクションを繰り返す

より多くの注文をサポートするには、プログラムを更新する必要があります。現在のコード構造では、冗長ステートメントを使用して6つの注文をサポートしています。冗長性は扱いにくく、維持するのが困難です。

ループ式を使用してアクションを繰り返し、各注文を作成することで、構造を単純化できます。簡略化されたコードを使用すると、多数の注文をすばやく作成できます。

  1. ではmain機能、削除次の文を。このコードブロックは、order変数を定義および設定し、自動車の注文のcar_factory関数とprintln!マクロを呼び出し、各注文をordersハッシュマップに挿入します。
// Order 6 cars
    // - Increment "order" after each request
    // - Add each order <K, V> pair to "orders" hash map
    // - Call println! to show order details from the hash map

    // Initialize order variable
    let mut order = 1;

    // Car order #1: Used, Hard top
    car = car_factory(order, 1000);
    orders.insert(order, car);
    println!("Car order {}: {:?}", order, orders.get(&order));

    ...

    // Car order #6: Used, Hard top
    order = order + 1;
    car = car_factory(order, 4000);
    orders.insert(order, car);
    println!("Car order {}: {:?}", order, orders.get(&order));

2. 削除されたステートメントを次のコードブロックに置き換えます。

// Start with zero miles
    let mut miles = 0;

    todo!("Add a loop expression to fulfill orders for 6 cars, initialize `order` variable to 1") {

        // Call car_factory to fulfill order
        // Add order <K, V> pair to "orders" hash map
        // Call println! to show order details from the hash map        
        car = car_factory(order, miles);
        orders.insert(order, car);
        println!("Car order {}: {:?}", order, orders.get(&order));

        // Reset miles for order variety
        if miles == 2100 {
            miles = 0;
        } else {
            miles = miles + 700;
        }
    }

3. アクションを繰り返すループ式を追加して、6台の車の注文を作成します。order1に初期化された変数が必要です。

4. プログラムをビルドします。コードがエラーなしでコンパイルされることを確認してください。

次の例のような出力が表示されます。

Car order 1: Some(Car { color: "Blue", motor: Manual, roof: true, age: ("New", 0) })
Car order 2: Some(Car { color: "Green", motor: SemiAuto, roof: false, age: ("Used", 700) })
Car order 3: Some(Car { color: "Red", motor: Automatic, roof: true, age: ("Used", 1400) })
Car order 4: Some(Car { color: "Silver", motor: SemiAuto, roof: false, age: ("Used", 2100) })
Car order 5: Some(Car { color: "Blue", motor: Manual, roof: true, age: ("New", 0) })
Car order 6: Some(Car { color: "Green", motor: Automatic, roof: true, age: ("Used", 700) })

車の注文を11に増やす

 プログラムは現在、ループを使用して6台の車の注文を処理しています。6台以上注文するとどうなりますか?

  1. main関数のループ式を更新して、11台の車を注文します。
    todo!("Update the loop expression to create 11 cars");

2. プログラムを再構築します。実行時に、プログラムはパニックになります!

Compiling playground v0.0.1 (/playground)
    Finished dev [unoptimized + debuginfo] target(s) in 1.26s
    Running `target/debug/playground`
thread 'main' panicked at 'index out of bounds: the len is 4 but the index is 4', src/main.rs:34:29

この問題を解決する方法を見てみましょう。

ループ式で実行時のパニックを防ぐ

このcar_factory関数では、if / else式を使用colorして、colors配列のインデックスの値を確認します。

// Prevent panic: Check color index for colors array, reset as needed
    // Valid color = 1, 2, 3, or 4
    // If color > 4, reduce color to valid index
    let mut color = order as usize;
    if color > 4 {        
        // color = 5 --> index 1, 6 --> 2, 7 --> 3, 8 --> 4
        color = color - 4;
    }

colors配列には4つの要素を持ち、かつ有効なcolor場合は、インデックスの範囲は0〜3の条件式をチェックしているcolor私たちはをチェックしません(インデックスが4よりも大きい場合color、その後の関数で4に等しいインデックスへのときに我々のインデックスを車の色を割り当てる配列では、インデックス値から1を減算しますcolor - 1color値4はcolors[3]、配列と同様に処理されます。)

現在のif / else式は、8台以下の車を注文するときの実行時のパニックを防ぐためにうまく機能します。しかし、11台の車を注文すると、プログラムは9番目の注文でパニックになります。より堅牢になるように式を調整する必要があります。この改善を行うために、別のループ式を使用します。

  1. ではcar_factory機能、ループ式であれば/他の条件文を交換してください。colorインデックス値が4より大きい場合に実行時のパニックを防ぐために、次の擬似コードステートメントを修正してください。
// Prevent panic: Check color index, reset as needed
    // If color = 1, 2, 3, or 4 - no change needed
    // If color > 4, reduce to color to a valid index
    let mut color = order as usize;
    todo!("Replace `if/else` condition with a loop to prevent run-time panic for color > 4");

ヒント

この場合、if / else条件からループ式への変更は実際には非常に簡単です。

2. プログラムをビルドします。コードがエラーなしでコンパイルされることを確認してください。

次の出力が表示されます。

Car order 1: Some(Car { color: "Blue", motor: Manual, roof: true, age: ("New", 0) })
Car order 2: Some(Car { color: "Green", motor: SemiAuto, roof: false, age: ("Used", 700) })
Car order 3: Some(Car { color: "Red", motor: Automatic, roof: true, age: ("Used", 1400) })
Car order 4: Some(Car { color: "Silver", motor: SemiAuto, roof: false, age: ("Used", 2100) })
Car order 5: Some(Car { color: "Blue", motor: Manual, roof: true, age: ("New", 0) })
Car order 6: Some(Car { color: "Green", motor: Automatic, roof: true, age: ("Used", 700) })
Car order 7: Some(Car { color: "Red", motor: Manual, roof: true, age: ("Used", 1400) })
Car order 8: Some(Car { color: "Silver", motor: SemiAuto, roof: false, age: ("Used", 2100) })
Car order 9: Some(Car { color: "Blue", motor: Automatic, roof: true, age: ("New", 0) })
Car order 10: Some(Car { color: "Green", motor: SemiAuto, roof: false, age: ("Used", 700) })
Car order 11: Some(Car { color: "Red", motor: Manual, roof: true, age: ("Used", 1400) })

概要

このモジュールでは、Rustで使用できるさまざまなループ式を調べ、ハッシュマップの操作方法を発見しました。データは、キーと値のペアとしてハッシュマップに保存されます。ハッシュマップは拡張可能です。

loop手動でプロセスを停止するまでの式は、アクションを繰り返します。while式をループして、条件が真である限りアクションを繰り返すことができます。このfor式は、データ収集を反復処理するために使用されます。

この演習では、自動車プログラムを拡張して、繰り返されるアクションをループし、すべての注文を処理しました。注文を追跡するためにハッシュマップを実装しました。

このラーニングパスの次のモジュールでは、Rustコードでエラーと障害がどのように処理されるかについて詳しく説明します。

 リンク: https://docs.microsoft.com/en-us/learn/modules/rust-loop-expressions/

#rust #Beginners 

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A Django Plugin for Creating AJAX Driven Forms in Bootstrap Modal

Django Bootstrap Modal Forms

A Django plugin for creating AJAX driven forms in Bootstrap modal.

Test and experiment on your machine

This repository includes Dockerfile and docker-compose.yml files so you can easily setup and start to experiment with django-bootstrap-modal-forms running inside of a container on your local machine. Any changes you make in bootstrap_modal_forms, examples and test folders are reflected in the container (see docker-compose.yml) and the data stored in sqlite3 database are persistent even if you remove stopped container. Follow the steps below to run the app:

$ clone repository
$ cd django-bootstrap-modal-forms
$ docker compose up (use -d flag to run app in detached mode in the background)
$ visit 0.0.0.0:8000

Installation

Install django-bootstrap-modal-forms:

$ pip install django-bootstrap-modal-forms

Add bootstrap_modal_forms to your INSTALLED_APPS in settings.py:

INSTALLED_APPS = [
    ...
    'bootstrap_modal_forms',
    ...
]

Include Bootstrap, jQuery and jquery.bootstrap.modal.forms.js on every page where you would like to set up the AJAX driven Django forms in Bootstrap modal.

IMPORTANT: Adjust Bootstrap and jQuery file paths to match yours, but include jquery.bootstrap.modal.forms.js exactly as in code bellow.

<head>
    <link rel="stylesheet" href="{% static 'assets/css/bootstrap.css' %}">
</head>

<body>
    <script src="{% static 'assets/js/bootstrap.js' %}"></script>
    <script src="{% static 'assets/js/jquery.js' %}"></script>
    <script src="{% static 'js/jquery.bootstrap.modal.forms.js' %}"></script>
    <!-- You can alternatively load the minified version -->
    <script src="{% static 'js/jquery.bootstrap.modal.forms.min.js' %}"></script>
</body>

How it works?

index.html

<script type="text/javascript">
$(document).ready(function() {

    $("#create-book").modalForm({
        formURL: "{% url 'create_book' %}"
    });

});
</script>
  1. Click event on html element instantiated with modalForm opens modal
  2. Form at formURL is appended to the modal
  3. On submit the form is POSTed via AJAX request to formURL
  4. Unsuccessful POST request returns errors, which are shown in modal
  5. Successful POST request submits the form and redirects to success_url and shows success_message, which are both defined in related Django view

Usage

1. Form

Define BookModelForm and inherit built-in form BSModalModelForm.

forms.py

from .models import Book
from bootstrap_modal_forms.forms import BSModalModelForm

class BookModelForm(BSModalModelForm):
    class Meta:
        model = Book
        fields = ['title', 'author', 'price']

2. Form's html

Define form's html and save it as Django template.

  • Bootstrap 4 modal elements are used in this example.
  • Form will POST to formURL defined in #6.
  • Add class="invalid" or custom errorClass (see paragraph Options) to the elements that wrap the fields.
  • class="invalid" acts as a flag for the fields having errors after the form has been POSTed.
book/create_book.html

<form method="post" action="">
  {% csrf_token %}

 <div class="modal-header">
    <h5 class="modal-title">Create new Book</h5>
    <button type="button" class="close" data-dismiss="modal" aria-label="Close">
      <span aria-hidden="true">&times;</span>
    </button>
  </div>

  <div class="modal-body">
    {% for field in form %}
      <div class="form-group{% if field.errors %} invalid{% endif %}">
        <label for="{{ field.id_for_label }}">{{ field.label }}</label>
        {{ field }}
        {% for error in field.errors %}
          <p class="help-block">{{ error }}</p>
        {% endfor %}
      </div>
    {% endfor %}
  </div>

  <div class="modal-footer">
    <button type="button" class="btn btn-default" data-dismiss="modal">Close</button>
    <button type="submit" class="btn btn-primary">Create</button>
  </div>

</form>

3. Class-based view

Define a class-based view BookCreateView and inherit from built-in generic view BSModalCreateView. BookCreateView processes the form defined in #1, uses the template defined in #2 and redirects to success_url showing success_message.

views.py

from django.urls import reverse_lazy
from .forms import BookModelForm
from .models import Book
from bootstrap_modal_forms.generic import BSModalCreateView

class BookCreateView(BSModalCreateView):
    template_name = 'examples/create_book.html'
    form_class = BookModelForm
    success_message = 'Success: Book was created.'
    success_url = reverse_lazy('index')

4. URL for the view

Define URL for the view in #3.

from django.urls import path
from books import views

urlpatterns = [
    path('', views.Index.as_view(), name='index'),
    path('create/', views.BookCreateView.as_view(), name='create_book'),
]

5. Bootstrap modal and trigger element

Define the Bootstrap modal window and html element triggering modal opening.

  • Single modal can be used for multiple modalForms in single template (see #6).
  • When using multiple modals on the same page each modal should have unique id and the same value should also be set as modalID option when instantiating modalForm on trigger element.
  • Trigger element (in this example button with id="create-book") is used for instantiation of modalForm in #6.
  • Any element can be trigger element as long as modalForm is bound to it.
  • Click event on trigger element loads form's html from #2 within <div class="modal-content"></div> and sets action attribute of the form to formURL set in #6.
index.html

<div class="modal fade" tabindex="-1" role="dialog" id="modal">
  <div class="modal-dialog" role="document">
    <div class="modal-content"></div>
  </div>
</div>

<!-- Create book button -->
<button id="create-book" class="btn btn-primary" type="button" name="button">Create book</button>

6. modalForm

Add script to the template from #5 and bind the modalForm to the trigger element. Set BookCreateView URL defined in #4 as formURL property of modalForm.

  • If you want to create more modalForms in single template using the single modal window from #5, repeat steps #1 to #4, create new trigger element as in #5 and bind the new modalForm with unique URL to it.
  • Default values for modalID, modalContent, modalForm and errorClass are used in this example, while formURL is customized. If you customize any other option adjust the code of the above examples accordingly.
index.html

<script type="text/javascript">
$(document).ready(function() {

    $("#create-book").modalForm({
        formURL: "{% url 'create_book' %}"
    });

});
</script>

Async create/update with or without modal closing on submit

Set asyncUpdate and asyncSettings settings to create or update objects without page redirection to successUrl and define whether a modal should close or stay opened after form submission. See comments in example below and paragraph modalForm options for explanation of asyncSettings. See examples on how to properly reinstantiate modal forms for all CRUD buttons when using async options.
index.html

<!-- asyncSettings.dataElementId -->
<table id="books-table" class="table">
  <thead>
    ...
  </thead>
  <tbody>
  {% for book in books %}
    <tr>
        ...
        <!-- Update book buttons -->
        <button type="button" class="update-book btn btn-sm btn-primary" data-form-url="{% url 'update_book' book.pk %}">
          <span class="fa fa-pencil"></span>
        </button>
        ...
      </td>
    </tr>
  {% endfor %}
  </tbody>
</table>

<script type="text/javascript">
    $(function () {
        ...

        # asyncSettings.successMessage
        var asyncSuccessMessage = [
          "<div ",
          "style='position:fixed;top:0;z-index:10000;width:100%;border-radius:0;' ",
          "class='alert alert-icon alert-success alert-dismissible fade show mb-0' role='alert'>",
          "Success: Book was updated.",
          "<button type='button' class='close' data-dismiss='alert' aria-label='Close'>",
          "<span aria-hidden='true'>&times;</span>",
          "</button>",
          "</div>",
          "<script>",
          "$('.alert').fadeTo(2000, 500).slideUp(500, function () {$('.alert').slideUp(500).remove();});",
          "<\/script>"
        ].join();

        # asyncSettings.addModalFormFunction
        function updateBookModalForm() {
          $(".update-book").each(function () {
            $(this).modalForm({
              formURL: $(this).data("form-url"),
              asyncUpdate: true,
              asyncSettings: {
                closeOnSubmit: false,
                successMessage: asyncSuccessMessage
                dataUrl: "books/",
                dataElementId: "#books-table",
                dataKey: "table",
                addModalFormFunction: updateBookModalForm
              }
            });
          });
        }
        updateBookModalForm();

        ...
    });
</script>
urls.py

from django.urls import path
from . import views

urlpatterns = [
    ...
    # asyncSettings.dataUrl
    path('books/', views.books, name='books'),
    ...
]
views.py

from django.http import JsonResponse
from django.template.loader import render_to_string
from .models import Book

def books(request):
    data = dict()
    if request.method == 'GET':
        books = Book.objects.all()
        # asyncSettings.dataKey = 'table'
        data['table'] = render_to_string(
            '_books_table.html',
            {'books': books},
            request=request
        )
        return JsonResponse(data)

modalForm options

modalID

Sets the custom id of the modal. Default: "#modal"

modalContent

Sets the custom class of the element to which the form's html is appended. If you change modalContent to the custom class, you should also change modalForm accordingly. To keep Bootstrap's modal style you should than copy Bootstrap's style for modal-content and set it to your new modalContent class. Default: ".modal-content"

modalForm

Sets the custom form selector. Default: ".modal-content form"

formURL

Sets the url of the form's view and html. Default: null

isDeleteForm

Defines if form is used for deletion. Should be set to true for deletion forms. Default: false

errorClass

Sets the custom class for the form fields having errors. Default: ".invalid"

asyncUpdate

Sets asynchronous content update after form submission. Default: false

asyncSettings.closeOnSubmit

Sets whether modal closes or not after form submission. Default: false

asyncSettings.successMessage

Sets successMessage shown after succesful for submission. Should be set to string defining message element. See asyncSuccessMessage example above. Default: null

asyncSettings.dataUrl

Sets url of the view returning new queryset = all of the objects plus newly created or updated one after asynchronous update. Default: null

asyncSettings.dataElementId

Sets the id of the element which rerenders asynchronously updated queryset. Default: null

asyncSettings.dataKey

Sets the key containing asynchronously updated queryset in the data dictionary returned from the view providing updated queryset. Default: null

asyncSettings.addModalFormFunction

Sets the method needed for reinstantiation of event listeners on buttons (single or all CRUD buttons) after asynchronous update. Default: null

modalForm default settings object and it's structure

triggerElement.modalForm({
    modalID: "#modal",
    modalContent: ".modal-content",
    modalForm: ".modal-content form",
    formURL: null,
    isDeleteForm: false,
    errorClass: ".invalid",
    asyncUpdate: false,
    asyncSettings: {
        closeOnSubmit: false,
        successMessage: null,
        dataUrl: null,
        dataElementId: null,
        dataKey: null,
        addModalFormFunction: null
    }
});

Forms

Import forms with from bootstrap_modal_forms.forms import BSModalForm.

BSModalForm

Inherits PopRequestMixin and Django's forms.Form.

BSModalModelForm

Inherits PopRequestMixin, CreateUpdateAjaxMixin and Django's forms.ModelForm.

Mixins

Import mixins with from bootstrap_modal_forms.mixins import PassRequestMixin.

PassRequestMixin

Puts the request into the form's kwargs.

PopRequestMixin

Pops request out of the kwargs and attaches it to the form's instance.

CreateUpdateAjaxMixin

Saves or doesn't save the object based on the request type.

DeleteMessageMixin

Deletes object if request is not ajax request.

LoginAjaxMixin

Authenticates user if request is not ajax request.

Generic views

Import generic views with from bootstrap_modal_forms.generic import BSModalFormView.

BSModalFormView

Inherits PassRequestMixin and Django's generic.FormView.

BSModalCreateView

Inherits PassRequestMixin and Django's SuccessMessageMixin and generic.CreateView.

BSModalUpdateView

Inherits PassRequestMixin and Django's SuccessMessageMixin and generic.UpdateView.

BSModalReadView

Inherits Django's generic.DetailView.

BSModalDeleteView

Inherits DeleteMessageMixin and Django's generic.DeleteView.

Examples

To see django-bootstrap-modal-forms in action clone the repository and run the examples locally:

$ git clone https://github.com/trco/django-bootstrap-modal-forms.git
$ cd django-bootstrap-modal-forms
$ pip install -r requirements.txt
$ python manage.py migrate
$ python manage.py runserver

Tests

Run unit and functional tests inside of project folder:

$ python manage.py test

Example 1: Signup form in Bootstrap modal

For explanation how all the parts of the code work together see paragraph Usage. To test the working solution presented here clone and run Examples.

forms.py

from django.contrib.auth.forms import UserCreationForm
from django.contrib.auth.models import User
from bootstrap_modal_forms.mixins import PopRequestMixin, CreateUpdateAjaxMixin


class CustomUserCreationForm(PopRequestMixin, CreateUpdateAjaxMixin,
                             UserCreationForm):
    class Meta:
        model = User
        fields = ['username', 'password1', 'password2']
signup.html

{% load widget_tweaks %}

<form method="post" action="">
  {% csrf_token %}

  <div class="modal-header">
    <h3 class="modal-title">Sign up</h3>
    <button type="button" class="close" data-dismiss="modal" aria-label="Close">
      <span aria-hidden="true">&times;</span>
    </button>
  </div>

  <div class="modal-body">

    <div class="{% if form.non_field_errors %}invalid{% endif %} mb-2">
      {% for error in form.non_field_errors %}
        {{ error }}
      {% endfor %}
    </div>

    {% for field in form %}
      <div class="form-group">
        <label for="{{ field.id_for_label }}">{{ field.label }}</label>
        {% render_field field class="form-control" placeholder=field.label %}
        <div class="{% if field.errors %} invalid{% endif %}">
          {% for error in field.errors %}
            <p class="help-block">{{ error }}</p>
          {% endfor %}
        </div>
      </div>
    {% endfor %}
  </div>

  <div class="modal-footer">
    <button type="submit" class="btn btn-primary">Sign up</button>
  </div>

</form>
views.py

from django.urls import reverse_lazy
from bootstrap_modal_forms.generic import BSModalCreateView
from .forms import CustomUserCreationForm

class SignUpView(BSModalCreateView):
    form_class = CustomUserCreationForm
    template_name = 'examples/signup.html'
    success_message = 'Success: Sign up succeeded. You can now Log in.'
    success_url = reverse_lazy('index')
urls.py

from django.urls import path
from . import views

app_name = 'accounts'
urlpatterns = [
    path('signup/', views.SignUpView.as_view(), name='signup')
]
.html file containing modal, trigger element and script instantiating modalForm

<div class="modal fade" tabindex="-1" role="dialog" id="modal">
  <div class="modal-dialog" role="document">
    <div class="modal-content"></div>
  </div>
</div>

<button id="signup-btn" class="btn btn-primary" type="button" name="button">Sign up</button>

<script type="text/javascript">
  $(function () {
    // Sign up button
    $("#signup-btn").modalForm({
        formURL: "{% url 'signup' %}"
    });
  });
</script>

Example 2: Login form in Bootstrap modal

For explanation how all the parts of the code work together see paragraph Usage. To test the working solution presented here clone and run Examples.

You can set the login redirection by setting the LOGIN_REDIRECT_URL in settings.py.

You can also set the custom login redirection by:

  1. Adding success_url to the extra_context of CustomLoginView
  2. Setting this success_url variable as a value of the hidden input field with name="next" within the Login form html
forms.py

from django.contrib.auth.forms import AuthenticationForm
from django.contrib.auth.models import User

class CustomAuthenticationForm(AuthenticationForm):
    class Meta:
        model = User
        fields = ['username', 'password']
login.html

{% load widget_tweaks %}

<form method="post" action="">
  {% csrf_token %}

  <div class="modal-header">
    <h3 class="modal-title">Log in</h3>
    <button type="button" class="close" data-dismiss="modal" aria-label="Close">
      <span aria-hidden="true">&times;</span>
    </button>
  </div>

  <div class="modal-body">

    <div class="{% if form.non_field_errors %}invalid{% endif %} mb-2">
      {% for error in form.non_field_errors %}
        {{ error }}
      {% endfor %}
    </div>

    {% for field in form %}
      <div class="form-group">
        <label for="{{ field.id_for_label }}">{{ field.label }}</label>
        {% render_field field class="form-control" placeholder=field.label %}
        <div class="{% if field.errors %} invalid{% endif %}">
          {% for error in field.errors %}
            <p class="help-block">{{ error }}</p>
          {% endfor %}
        </div>
      </div>
    {% endfor %}

    <!-- Hidden input field for custom redirection after successful login -->
    <input type="hidden" name="next" value="{{ success_url }}">
  </div>

  <div class="modal-footer">
    <button type="submit" class="btn btn-primary">Log in</button>
  </div>

</form>
views.py

from django.urls import reverse_lazy
from bootstrap_modal_forms.generic import BSModalLoginView
from .forms import CustomAuthenticationForm

class CustomLoginView(BSModalLoginView):
    authentication_form = CustomAuthenticationForm
    template_name = 'examples/login.html'
    success_message = 'Success: You were successfully logged in.'
    extra_context = dict(success_url=reverse_lazy('index'))
urls.py

from django.urls import path
from . import views

app_name = 'accounts'
urlpatterns = [
    path('login/', views.CustomLoginView.as_view(), name='login')
]
.html file containing modal, trigger element and script instantiating modalForm

<div class="modal fade" tabindex="-1" role="dialog" id="modal">
  <div class="modal-dialog" role="document">
    <div class="modal-content"></div>
  </div>
</div>

<button id="login-btn" class="btn btn-primary" type="button" name="button">Sign up</button>

<script type="text/javascript">
  $(function () {
    // Log in button
    $("#login-btn").modalForm({
        formURL: "{% url 'login' %}"
    });
  });
</script>

Example 3: Django's forms.ModelForm (CRUD forms) in Bootstrap modal

For explanation how all the parts of the code work together see paragraph Usage. To test the working solution presented here clone and run Examples.

forms.py

from .models import Book
from bootstrap_modal_forms.forms import BSModalModelForm


class BookModelForm(BSModalModelForm):
    class Meta:
        model = Book
        exclude = ['timestamp']
create_book.html

{% load widget_tweaks %}

<form method="post" action="">
  {% csrf_token %}

  <div class="modal-header">
    <h3 class="modal-title">Create Book</h3>
    <button type="button" class="close" data-dismiss="modal" aria-label="Close">
      <span aria-hidden="true">&times;</span>
    </button>
  </div>

  <div class="modal-body">

    <div class="{% if form.non_field_errors %}invalid{% endif %} mb-2">
      {% for error in form.non_field_errors %}
        {{ error }}
      {% endfor %}
    </div>

    {% for field in form %}
      <div class="form-group">
        <label for="{{ field.id_for_label }}">{{ field.label }}</label>
        {% render_field field class="form-control" placeholder=field.label %}
        <div class="{% if field.errors %} invalid{% endif %}">
          {% for error in field.errors %}
            <p class="help-block">{{ error }}</p>
          {% endfor %}
        </div>
      </div>
    {% endfor %}
  </div>

  <div class="modal-footer">
    <button type="submit" class="btn btn-primary">Create</button>
  </div>

</form>
update_book.html

{% load widget_tweaks %}

<form method="post" action="">
  {% csrf_token %}

  <div class="modal-header">
    <h3 class="modal-title">Update Book</h3>
    <button type="button" class="close" data-dismiss="modal" aria-label="Close">
      <span aria-hidden="true">&times;</span>
    </button>
  </div>

  <div class="modal-body">
    <div class="{% if form.non_field_errors %}invalid{% endif %} mb-2">
      {% for error in form.non_field_errors %}
        {{ error }}
      {% endfor %}
    </div>

    {% for field in form %}
      <div class="form-group">
        <label for="{{ field.id_for_label }}">{{ field.label }}</label>
        {% render_field field class="form-control" placeholder=field.label %}
        <div class="{% if field.errors %} invalid{% endif %}">
          {% for error in field.errors %}
            <p class="help-block">{{ error }}</p>
          {% endfor %}
        </div>
      </div>
    {% endfor %}
  </div>

  <div class="modal-footer">
    <button type="submit" class="btn btn-primary">Update</button>
  </div>

</form>
read_book.html

{% load widget_tweaks %}

<div class="modal-header">
  <h3 class="modal-title">Book details</h3>
  <button type="button" class="close" data-dismiss="modal" aria-label="Close">
    <span aria-hidden="true">&times;</span>
  </button>
</div>

<div class="modal-body">
  <div class="">
    Title: {{ book.title }}
  </div>
  <div class="">
    Author: {{ book.author }}
  </div>
  <div class="">
    Price: {{ book.price }} €
  </div>
</div>

<div class="modal-footer">
  <button type="button" class="btn btn-default" data-dismiss="modal">Close</button>
</div>
{% load widget_tweaks %}

<form method="post" action="">
  {% csrf_token %}

  <div class="modal-header">
    <h3 class="modal-title">Delete Book</h3>
    <button type="button" class="close" data-dismiss="modal" aria-label="Close">
      <span aria-hidden="true">&times;</span>
    </button>
  </div>

  <div class="modal-body">
    <p>Are you sure you want to delete book with title
      <strong>{{ book.title }}</strong>?</p>
  </div>

  <div class="modal-footer">
    <button type="submit" class="btn btn-danger">Delete</button>
  </div>

</form>
views.py

from django.urls import reverse_lazy
from django.views import generic
from .forms import BookModelForm
from .models import Book
from bootstrap_modal_forms.generic import (
  BSModalCreateView,
  BSModalUpdateView,
  BSModalReadView,
  BSModalDeleteView
)

class Index(generic.ListView):
    model = Book
    context_object_name = 'books'
    template_name = 'index.html'

# Create
class BookCreateView(BSModalCreateView):
    template_name = 'examples/create_book.html'
    form_class = BookModelForm
    success_message = 'Success: Book was created.'
    success_url = reverse_lazy('index')

# Update
class BookUpdateView(BSModalUpdateView):
    model = Book
    template_name = 'examples/update_book.html'
    form_class = BookModelForm
    success_message = 'Success: Book was updated.'
    success_url = reverse_lazy('index')

# Read
class BookReadView(BSModalReadView):
    model = Book
    template_name = 'examples/read_book.html'

# Delete
class BookDeleteView(BSModalDeleteView):
    model = Book
    template_name = 'examples/delete_book.html'
    success_message = 'Success: Book was deleted.'
    success_url = reverse_lazy('index')
urls.py

from django.urls import path
from books import views

urlpatterns = [
    path('', views.Index.as_view(), name='index'),
    path('create/', views.BookCreateView.as_view(), name='create_book'),
    path('update/<int:pk>', views.BookUpdateView.as_view(), name='update_book'),
    path('read/<int:pk>', views.BookReadView.as_view(), name='read_book'),
    path('delete/<int:pk>', views.BookDeleteView.as_view(), name='delete_book')
]
.html file containing modal, trigger elements and script instantiating modalForms

<!-- Modal 1 with id="create-book"-->
<div class="modal fade" id="create-modal" tabindex="-1" role="dialog" aria-hidden="true">
  <div class="modal-dialog">
    <div class="modal-content">
    </div>
  </div>
</div>

<!-- Modal 2 with id="modal" -->
<div class="modal fade" tabindex="-1" role="dialog" id="modal">
  <div class="modal-dialog" role="document">
    <div class="modal-content"></div>
  </div>
</div>

<!-- Create book button -->
<button id="create-book" class="btn btn-primary" type="button" name="button">Create book</button>

{% for book in books %}
    <div class="text-center">
      <!-- Read book buttons -->
      <button type="button" class="read-book bs-modal btn btn-sm btn-primary" data-form-url="{% url 'read_book' book.pk %}">
        <span class="fa fa-eye"></span>
      </button>
      <!-- Update book buttons -->
      <button type="button" class="update-book bs-modal btn btn-sm btn-primary" data-form-url="{% url 'update_book' book.pk %}">
        <span class="fa fa-pencil"></span>
      </button>
      <!-- Delete book buttons -->
      <button type="button" class="delete-book bs-modal btn btn-sm btn-danger" data-form-url="{% url 'delete_book' book.pk %}">
        <span class="fa fa-trash"></span>
      </button>
    </div>
{% endfor %}

<script type="text/javascript">
  $(function () {

    // Read book buttons
    $(".read-book").each(function () {
        $(this).modalForm({formURL: $(this).data("form-url")});
    });

    // Delete book buttons - formURL is retrieved from the data of the element
    $(".delete-book").each(function () {
        $(this).modalForm({formURL: $(this).data("form-url"), isDeleteForm: true});
    });

    // Create book button opens form in modal with id="create-modal"
    $("#create-book").modalForm({
        formURL: "{% url 'create_book' %}",
        modalID: "#create-modal"
    });

  });
</script>
  • See the difference between button triggering Create action and buttons triggering Read, Update and Delete actions.
  • Within the for loop in .html file the data-form-url attribute of each Update, Read and Delete button should be set to relevant URL with pk argument of the object to be updated, read or deleted.
  • These data-form-url URLs should than be set as formURLs for modalForms bound to the buttons.

Example 4: Django's forms.Form in Bootstrap modal

For explanation how all the parts of the code work together see paragraph Usage. To test the working solution presented here clone and run Examples.

forms.py

from bootstrap_modal_forms.forms import BSModalForm

class BookFilterForm(BSModalForm):
    type = forms.ChoiceField(choices=Book.BOOK_TYPES)

    class Meta:
        fields = ['type']
filter_book.html

{% load widget_tweaks %}

<form method="post" action="">
  {% csrf_token %}

  <div class="modal-header">
    <h3 class="modal-title">Filter Books</h3>
    <button type="button" class="close" data-dismiss="modal" aria-label="Close">
      <span aria-hidden="true">&times;</span>
    </button>
  </div>

  <div class="modal-body">
    <div class="{% if form.non_field_errors %}invalid{% endif %} mb-2">
      {% for error in form.non_field_errors %}
        {{ error }}
      {% endfor %}
    </div>

    {% for field in form %}
      <div class="form-group">
        <label for="{{ field.id_for_label }}">{{ field.label }}</label>
        {% render_field field class="form-control" placeholder=field.label %}
        <div class="{% if field.errors %} invalid{% endif %}">
          {% for error in field.errors %}
            <p class="help-block">{{ error }}</p>
          {% endfor %}
        </div>
      </div>
    {% endfor %}
  </div>

  <div class="modal-footer">
    <button type="submit" class="btn btn-primary">Filter</button>
  </div>

</form>
views.py

class BookFilterView(BSModalFormView):
    template_name = 'examples/filter_book.html'
    form_class = BookFilterForm

    def form_valid(self, form):
        self.filter = '?type=' + form.cleaned_data['type']
        response = super().form_valid(form)
        return response

    def get_success_url(self):
        return reverse_lazy('index') + self.filter
urls.py

from django.urls import path
from . import views

app_name = 'accounts'
urlpatterns = [
    path('filter/', views.BookFilterView.as_view(), name='filter_book'),
]
index.html

  ...
  <button id="filter-book" class="filter-book btn btn-primary" type="button" name="button" data-form-url="{% url 'filter_book' %}">
    <span class="fa fa-filter mr-2"></span>Filter books
  </button>
  ...

  <script type="text/javascript">
    $(function () {
      ...
      $("#filter-book").each(function () {
          $(this).modalForm({formURL: $(this).data('form-url')});
      });
      ...
    });
  </script>

Contribute

This is an Open Source project and any contribution is appreciated.

Live Demo

Demo


Download Details:

Author: trco
Source Code: https://github.com/trco/django-bootstrap-modal-forms

License: MIT license

#django #bootstrap #ajax 

ERIC  MACUS

ERIC MACUS

1647540000

Substrate Knowledge Map For Hackathon Participants

Substrate Knowledge Map for Hackathon Participants

The Substrate Knowledge Map provides information that you—as a Substrate hackathon participant—need to know to develop a non-trivial application for your hackathon submission.

The map covers 6 main sections:

  1. Introduction
  2. Basics
  3. Preliminaries
  4. Runtime Development
  5. Polkadot JS API
  6. Smart Contracts

Each section contains basic information on each topic, with links to additional documentation for you to dig deeper. Within each section, you'll find a mix of quizzes and labs to test your knowledge as your progress through the map. The goal of the labs and quizzes is to help you consolidate what you've learned and put it to practice with some hands-on activities.

Introduction

One question we often get is why learn the Substrate framework when we can write smart contracts to build decentralized applications?

The short answer is that using the Substrate framework and writing smart contracts are two different approaches.

Smart contract development

Traditional smart contract platforms allow users to publish additional logic on top of some core blockchain logic. Since smart contract logic can be published by anyone, including malicious actors and inexperienced developers, there are a number of intentional safeguards and restrictions built around these public smart contract platforms. For example:

Fees: Smart contract developers must ensure that contract users are charged for the computation and storage they impose on the computers running their contract. With fees, block creators are protected from abuse of the network.

Sandboxed: A contract is not able to modify core blockchain storage or storage items of other contracts directly. Its power is limited to only modifying its own state, and the ability to make outside calls to other contracts or runtime functions.

Reversion: Contracts can be prone to undesirable situations that lead to logical errors when wanting to revert or upgrade them. Developers need to learn additional patterns such as splitting their contract's logic and data to ensure seamless upgrades.

These safeguards and restrictions make running smart contracts slower and more costly. However, it's important to consider the different developer audiences for contract development versus Substrate runtime development.

Building decentralized applications with smart contracts allows your community to extend and develop on top of your runtime logic without worrying about proposals, runtime upgrades, and so on. You can also use smart contracts as a testing ground for future runtime changes, but done in an isolated way that protects your network from any errors the changes might introduce.

In summary, smart contract development:

  • Is inherently safer to the network.
  • Provides economic incentives and transaction fee mechanisms that can't be directly controlled by the smart contract author.
  • Provides computational overhead to support graceful logical failures.
  • Has a low barrier to entry for developers and enables a faster pace of community interaction.

Substrate runtime development

Unlike traditional smart contract development, Substrate runtime development offers none of the network protections or safeguards. Instead, as a runtime developer, you have total control over how the blockchain behaves. However, this level of control also means that there is a higher barrier to entry.

Substrate is a framework for building blockchains, which almost makes comparing it to smart contract development like comparing apples and oranges. With the Substrate framework, developers can build smart contracts but that is only a fraction of using Substrate to its full potential.

With Substrate, you have full control over the underlying logic that your network's nodes will run. You also have full access for modifying and controlling each and every storage item across your runtime modules. As you progress through this map, you'll discover concepts and techniques that will help you to unlock the potential of the Substrate framework, giving you the freedom to build the blockchain that best suits the needs of your application.

You'll also discover how you can upgrade the Substrate runtime with a single transaction instead of having to organize a community hard-fork. Upgradeability is one of the primary design features of the Substrate framework.

In summary, runtime development:

  • Provides low level access to your entire blockchain.
  • Removes the overhead of built-in safety for performance.
  • Has a higher barrier of entry for developers.
  • Provides flexibility to customize full-stack application logic.

To learn more about using smart contracts within Substrate, refer to the Smart Contract - Overview page as well as the Polkadot Builders Guide.

Navigating the documentation

If you need any community support, please join the following channels based on the area where you need help:

Alternatively, also look for support on Stackoverflow where questions are tagged with "substrate" or on the Parity Subport repo.

Use the following links to explore the sites and resources available on each:

Substrate Developer Hub has the most comprehensive all-round coverage about Substrate, from a "big picture" explanation of architecture to specific technical concepts. The site also provides tutorials to guide you as your learn the Substrate framework and the API reference documentation. You should check this site first if you want to look up information about Substrate runtime development. The site consists of:

Knowledge Base: Explaining the foundational concepts of building blockchain runtimes using Substrate.

Tutorials: Hand-on tutorials for developers to follow. The first SIX tutorials show the fundamentals in Substrate and are recommended for every Substrate learner to go through.

How-to Guides: These resources are like the O'Reilly cookbook series written in a task-oriented way for readers to get the job done. Some examples of the topics overed include:

  • Setting up proper weight functions for extrinsic calls.
  • Using off-chain workers to fetch HTTP requests.
  • Writing tests for your pallets It can also be read from

API docs: Substrate API reference documentation.

Substrate Node Template provides a light weight, minimal Substrate blockchain node that you can set up as a local development environment.

Substrate Front-end template provides a front-end interface built with React using Polkadot-JS API to connect to any Substrate node. Developers are encouraged to start new Substrate projects based on these templates.

If you face any technical difficulties and need support, feel free to join the Substrate Technical matrix channel and ask your questions there.

Additional resources

Polkadot Wiki documents the specific behavior and mechanisms of the Polkadot network. The Polkadot network allows multiple blockchains to connect and pass messages to each other. On the wiki, you can learn about how Polkadot—built using Substrate—is customized to support inter-blockchain message passing.

Polkadot JS API doc: documents how to use the Polkadot-JS API. This JavaScript-based API allows developers to build custom front-ends for their blockchains and applications. Polkadot JS API provides a way to connect to Substrate-based blockchains to query runtime metadata and send transactions.

Quiz #1

👉 Submit your answers to Quiz #1

Basics

Set up your local development environment

Here you will set up your local machine to install the Rust compiler—ensuring that you have both stable and nightly versions installed. Both stable and nightly versions are required because currently a Substrate runtime is compiled to a native binary using the stable Rust compiler, then compiled to a WebAssembly (WASM) binary, which only the nightly Rust compiler can do.

Also refer to:

Lab #1

👉 Complete Lab #1: Run a Substrate node

Interact with a Substrate network using Polkadot-JS apps

Polkadot JS Apps is the canonical front-end to interact with any Substrate-based chain.

You can configure whichever endpoint you want it to connected to, even to your localhost running node. Refer to the following two diagrams.

  1. Click on the top left side showing your currently connected network:

assets/01-polkadot-app-endpoint.png

  1. Scroll to the bottom of the menu, open DEVELOPMENT, and choose either Local Node or Custom to specify your own endpoint.

assets/02-polkadot-app-select-endpoint.png

Quiz #2

👉 Complete Quiz #2

Lab #2

👉 Complete Lab #2: Using Polkadot-JS Apps

Notes: If you are connecting Apps to a custom chain (or your locally-running node), you may need to specify your chain's custom data types in JSON under Settings > Developer.

Polkadot-JS Apps only receives a series of bytes from the blockchain. It is up to the developer to tell it how to decode and interpret these custom data type. To learn more on this, refer to:

You will also need to create an account. To do so, follow these steps on account generation. You'll learn that you can also use the Polkadot-JS Browser Plugin (a Metamask-like browser extension to manage your Substrate accounts) and it will automatically be imported into Polkadot-JS Apps.

Notes: When you run a Substrate chain in development mode (with the --dev flag), well-known accounts (Alice, Bob, Charlie, etc.) are always created for you.

Lab #3

👉 Complete Lab #3: Create an Account

Preliminaries

You need to know some Rust programming concepts and have a good understanding on how blockchain technology works in order to make the most of developing with Substrate. The following resources will help you brush up in these areas.

Rust

You will need familiarize yourself with Rust to understand how Substrate is built and how to make the most of its capabilities.

If you are new to Rust, or need a brush up on your Rust knowledge, please refer to The Rust Book. You could still continue learning about Substrate without knowing Rust, but we recommend you come back to this section whenever in doubt about what any of the Rust syntax you're looking at means. Here are the parts of the Rust book we recommend you familiarize yourself with:

  • ch 1 - 10: These chapters cover the foundational knowledge of programming in Rust
  • ch 13: On iterators and closures
  • ch 18 - 19: On advanced traits and advanced types. Learn a bit about macros as well. You will not necessarily be writing your own macros, but you'll be using a lot of Substrate and FRAME's built-in macros to write your blockchain runtime.

How blockchains work

Given that you'll be writing a blockchain runtime, you need to know what a blockchain is, and how it works. The **Web3 Blockchain Fundamental MOOC Youtube video series provides a good basis for understanding key blockchain concepts and how blockchains work.

The lectures we recommend you watch are: lectures 1 - 7 and lecture 10. That's 8 lectures, or about 4 hours of video.

Quiz #3

👉 Complete Quiz #3

Substrate runtime development

High level architecture

To know more about the high level architecture of Substrate, please go through the Knowledge Base articles on Getting Started: Overview and Getting Started: Architecture.

In this document, we assume you will develop a Substrate runtime with FRAME (v2). This is what a Substrate node consists of.

assets/03-substrate-architecture.png

Each node has many components that manage things like the transaction queue, communicating over a P2P network, reaching consensus on the state of the blockchain, and the chain's actual runtime logic (aka the blockchain runtime). Each aspect of the node is interesting in its own right, and the runtime is particularly interesting because it contains the business logic (aka "state transition function") that codifies the chain's functionality. The runtime contains a collection of pallets that are configured to work together.

On the node level, Substrate leverages libp2p for the p2p networking layer and puts the transaction pool, consensus mechanism, and underlying data storage (a key-value database) on the node level. These components all work "under the hood", and in this knowledge map we won't cover them in detail except for mentioning their existence.

Quiz #4

👉 Complete Quiz #4

Runtime development topics

In our Developer Hub, we have a thorough coverage on various subjects you need to know to develop with Substrate. So here we just list out the key topics and reference back to Developer Hub. Please go through the following key concepts and the directed resources to know the fundamentals of runtime development.

Key Concept: Runtime, this is where the blockchain state transition function (the blockchain application-specific logic) is defined. It is about composing multiple pallets (can be understood as Rust modules) together in the runtime and hooking them up together.

Runtime Development: Execution, this article describes how a block is produced, and how transactions are selected and executed to reach the next "stage" in the blockchain.

Runtime Develpment: Pallets, this article describes what the basic structure of a Substrate pallet is consists of.

Runtime Development: FRAME, this article gives a high level overview of the system pallets Substrate already implements to help you quickly develop as a runtime engineer. Have a quick skim so you have a basic idea of the different pallets Substrate is made of.

Lab #4

👉 Complete Lab #4: Adding a Pallet into a Runtime

Runtime Development: Storage, this article describes how data is stored on-chain and how you could access them.

Runtime Development: Events & Errors, this page describe how external parties know what has happened in the blockchain, via the emitted events and errors when executing transactions.

Notes: All of the above concepts we leverage on the #[pallet::*] macro to define them in the code. If you are interested to learn more about what other types of pallet macros exist go to the FRAME macro API documentation and this doc on some frequently used Substrate macros.

Lab #5

👉 Complete Lab #5: Building a Proof-of-Existence dApp

Lab #6

👉 Complete Lab #6: Building a Substrate Kitties dApp

Quiz #5

👉 Complete Quiz #5

Polkadot JS API

Polkadot JS API is the javascript API for Substrate. By using it you can build a javascript front end or utility and interact with any Substrate-based blockchain.

The Substrate Front-end Template is an example of using Polkadot JS API in a React front-end.

  • Runtime Development: Metadata, this article describes the API allowing external parties to query what API is open for the chain. Polkadot JS API makes use of a chain's metadata to know what queries and functions are available from a chain to call.

Lab #7

👉 Complete Lab #7: Using Polkadot-JS API

Quiz #6

👉 Complete Quiz #6: Using Polkadot-JS API

Smart contracts

Learn about the difference between smart contract development vs Substrate runtime development, and when to use each here.

In Substrate, you can program smart contracts using ink!.

Quiz #7

👉 Complete Quiz #7: Using ink!

What we do not cover

A lot 😄

On-chain runtime upgrades. We have a tutorial on On-chain (forkless) Runtime Upgrade. This tutorial introduces how to perform and schedule a runtime upgrade as an on-chain transaction.

About transaction weight and fee, and benchmarking your runtime to determine the proper transaction cost.

Off-chain Features

There are certain limits to on-chain logic. For instance, computation cannot be too intensive that it affects the block output time, and computation must be deterministic. This means that computation that relies on external data fetching cannot be done on-chain. In Substrate, developers can run these types of computation off-chain and have the result sent back on-chain via extrinsics.

Tightly- and Loosely-coupled pallets, calling one pallet's functions from another pallet via trait specification.

Blockchain Consensus Mechansim, and a guide on customizing it to proof-of-work here.

Parachains: one key feature of Substrate is the capability of becoming a parachain for relay chains like Polkadot. You can develop your own application-specific logic in your chain and rely on the validator community of the relay chain to secure your network, instead of building another validator community yourself. Learn more with the following resources:

Terms clarification

  • Substrate: the blockchain development framework built for writing highly customized, domain-specific blockchains.
  • Polkadot: Polkadot is the relay chain blockchain, built with Substrate.
  • Kusama: Kusama is Polkadot's canary network, used to launch features before these features are launched on Polkadot. You could view it as a beta-network with real economic value where the state of the blockchain is never reset.
  • Web 3.0: is the decentralized internet ecosystem that, instead of apps being centrally stored in a few servers and managed by a sovereign party, it is an open, trustless, and permissionless network when apps are not controlled by a centralized entity.
  • Web3 Foundation: A foundation setup to support the development of decentralized web software protocols. Learn more about what they do on thier website.

Others


Author: substrate-developer-hub
Source Code: https://github.com/substrate-developer-hub/hackathon-knowledge-map
License: 

#blockchain #substrate 

Justen  Hintz

Justen Hintz

1663559281

To-do List App with HTML, CSS and JavaScript

Learn how to create a to-do list app with local storage using HTML, CSS and JavaScript. Build a Todo list application with HTML, CSS and JavaScript. Learn the basics to JavaScript along with some more advanced features such as LocalStorage for saving data to the browser.

HTML:

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>To Do List With Local Storage</title>
    <!-- Font Awesome Icons -->
    <link
      rel="stylesheet"
      href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/6.2.0/css/all.min.css"
    />
    <!-- Google Fonts -->
    <link
      href="https://fonts.googleapis.com/css2?family=Poppins:wght@400;500&display=swap"
      rel="stylesheet"
    />
    <!-- Stylesheet -->
    <link rel="stylesheet" href="style.css" />
  </head>
  <body>
    <div class="container">
      <div id="new-task">
        <input type="text" placeholder="Enter The Task Here..." />
        <button id="push">Add</button>
      </div>
      <div id="tasks"></div>
    </div>
    <!-- Script -->
    <script src="script.js"></script>
  </body>
</html>

CSS:

* {
  padding: 0;
  margin: 0;
  box-sizing: border-box;
}
body {
  background-color: #0b87ff;
}
.container {
  width: 90%;
  max-width: 34em;
  position: absolute;
  transform: translate(-50%, -50%);
  top: 50%;
  left: 50%;
}
#new-task {
  position: relative;
  background-color: #ffffff;
  padding: 1.8em 1.25em;
  border-radius: 0.3em;
  box-shadow: 0 1.25em 1.8em rgba(1, 24, 48, 0.15);
  display: grid;
  grid-template-columns: 9fr 3fr;
  gap: 1em;
}
#new-task input {
  font-family: "Poppins", sans-serif;
  font-size: 1em;
  border: none;
  border-bottom: 2px solid #d1d3d4;
  padding: 0.8em 0.5em;
  color: #111111;
  font-weight: 500;
}
#new-task input:focus {
  outline: none;
  border-color: #0b87ff;
}
#new-task button {
  font-family: "Poppins", sans-serif;
  font-weight: 500;
  font-size: 1em;
  background-color: #0b87ff;
  color: #ffffff;
  outline: none;
  border: none;
  border-radius: 0.3em;
  cursor: pointer;
}
#tasks {
  background-color: #ffffff;
  position: relative;
  padding: 1.8em 1.25em;
  margin-top: 3.8em;
  width: 100%;
  box-shadow: 0 1.25em 1.8em rgba(1, 24, 48, 0.15);
  border-radius: 0.6em;
}
.task {
  background-color: #ffffff;
  padding: 0.3em 0.6em;
  margin-top: 0.6em;
  display: flex;
  align-items: center;
  border-bottom: 2px solid #d1d3d4;
  cursor: pointer;
}
.task span {
  font-family: "Poppins", sans-serif;
  font-size: 0.9em;
  font-weight: 400;
}
.task button {
  color: #ffffff;
  padding: 0.8em 0;
  width: 2.8em;
  border-radius: 0.3em;
  border: none;
  outline: none;
  cursor: pointer;
}
.delete {
  background-color: #fb3b3b;
}
.edit {
  background-color: #0b87ff;
  margin-left: auto;
  margin-right: 3em;
}
.completed {
  text-decoration: line-through;
}

Javascript:

//Initial References
const newTaskInput = document.querySelector("#new-task input");
const tasksDiv = document.querySelector("#tasks");
let deleteTasks, editTasks, tasks;
let updateNote = "";
let count;

//Function on window load
window.onload = () => {
  updateNote = "";
  count = Object.keys(localStorage).length;
  displayTasks();
};

//Function to Display The Tasks
const displayTasks = () => {
  if (Object.keys(localStorage).length > 0) {
    tasksDiv.style.display = "inline-block";
  } else {
    tasksDiv.style.display = "none";
  }

  //Clear the tasks
  tasksDiv.innerHTML = "";

  //Fetch All The Keys in local storage
  let tasks = Object.keys(localStorage);
  tasks = tasks.sort();

  for (let key of tasks) {
    let classValue = "";

    //Get all values
    let value = localStorage.getItem(key);
    let taskInnerDiv = document.createElement("div");
    taskInnerDiv.classList.add("task");
    taskInnerDiv.setAttribute("id", key);
    taskInnerDiv.innerHTML = `<span id="taskname">${key.split("_")[1]}</span>`;
    //localstorage would store boolean as string so we parse it to boolean back
    let editButton = document.createElement("button");
    editButton.classList.add("edit");
    editButton.innerHTML = `<i class="fa-solid fa-pen-to-square"></i>`;
    if (!JSON.parse(value)) {
      editButton.style.visibility = "visible";
    } else {
      editButton.style.visibility = "hidden";
      taskInnerDiv.classList.add("completed");
    }
    taskInnerDiv.appendChild(editButton);
    taskInnerDiv.innerHTML += `<button class="delete"><i class="fa-solid fa-trash"></i></button>`;
    tasksDiv.appendChild(taskInnerDiv);
  }

  //tasks completed
  tasks = document.querySelectorAll(".task");
  tasks.forEach((element, index) => {
    element.onclick = () => {
      //local storage update
      if (element.classList.contains("completed")) {
        updateStorage(element.id.split("_")[0], element.innerText, false);
      } else {
        updateStorage(element.id.split("_")[0], element.innerText, true);
      }
    };
  });

  //Edit Tasks
  editTasks = document.getElementsByClassName("edit");
  Array.from(editTasks).forEach((element, index) => {
    element.addEventListener("click", (e) => {
      //Stop propogation to outer elements (if removed when we click delete eventually rhw click will move to parent)
      e.stopPropagation();
      //disable other edit buttons when one task is being edited
      disableButtons(true);
      //update input value and remove div
      let parent = element.parentElement;
      newTaskInput.value = parent.querySelector("#taskname").innerText;
      //set updateNote to the task that is being edited
      updateNote = parent.id;
      //remove task
      parent.remove();
    });
  });

  //Delete Tasks
  deleteTasks = document.getElementsByClassName("delete");
  Array.from(deleteTasks).forEach((element, index) => {
    element.addEventListener("click", (e) => {
      e.stopPropagation();
      //Delete from local storage and remove div
      let parent = element.parentElement;
      removeTask(parent.id);
      parent.remove();
      count -= 1;
    });
  });
};

//Disable Edit Button
const disableButtons = (bool) => {
  let editButtons = document.getElementsByClassName("edit");
  Array.from(editButtons).forEach((element) => {
    element.disabled = bool;
  });
};

//Remove Task from local storage
const removeTask = (taskValue) => {
  localStorage.removeItem(taskValue);
  displayTasks();
};

//Add tasks to local storage
const updateStorage = (index, taskValue, completed) => {
  localStorage.setItem(`${index}_${taskValue}`, completed);
  displayTasks();
};

//Function To Add New Task
document.querySelector("#push").addEventListener("click", () => {
  //Enable the edit button
  disableButtons(false);
  if (newTaskInput.value.length == 0) {
    alert("Please Enter A Task");
  } else {
    //Store locally and display from local storage
    if (updateNote == "") {
      //new task
      updateStorage(count, newTaskInput.value, false);
    } else {
      //update task
      let existingCount = updateNote.split("_")[0];
      removeTask(updateNote);
      updateStorage(existingCount, newTaskInput.value, false);
      updateNote = "";
    }
    count += 1;
    newTaskInput.value = "";
  }
});

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#html #css #javascript