6 Best Rust Asynchronous Library

In today's post we will learn about 6 Best Rust Asynchronous Library.

What is Asynchronous?

Asynchronous programming is a technique that enables your program to start a potentially long-running task and still be able to be responsive to other events while that task runs, rather than having to wait until that task has finished. Once that task has finished, your program is presented with the result.

Table of contents:

• Dpc/mioco - Scalable, coroutine-based, asynchronous IO handling library.
• Mio - MIO is a lightweight IO library for Rust with a focus on adding as little overhead as possible over the OS abstractions.
• Rust-lang/futures-rs - Zero-cost futures in Rust.
• TeaEntityLab/fpRust - Monad/MonadIO, Handler, Coroutine/doNotation, Functional Programming features for Rust.
• Xudong-Huang/may - Rust stackful coroutine library.
• Zonyitoo/coio-rs - A coroutine I/O library with a working-stealing scheduler.

1 - Dpc/mioco:

Scalable, coroutine-based, asynchronous IO handling library.

Mioco provides green-threads (aka fibers) like eg. Goroutines in Go, for Rust.

Status

This repo is a complete re-implementation of mioco. The code of previous versions was moved to mioco.pre-0.9.

The goals of new implementation:

•  switch to latest mio version
•  copy all the applicable good ideas from tokio reactor code
•  simplify the approach
  •  remove the exposed scheduler
•  model the API to be more like std library, less like mio
•  focus on synchronization primitives first
•  support async file IO (via worker threads)
•  port all the existing mioco features, tests, examples etc.

View on Github

2 - Mio:

MIO is a lightweight IO library for Rust with a focus on adding as little overhead as possible over the OS abstractions.

Mio is a fast, low-level I/O library for Rust focusing on non-blocking APIs and event notification for building high performance I/O apps with as little overhead as possible over the OS abstractions.

Usage

To use mio, first add this to your Cargo.toml:

[dependencies]
mio = "0.8"

Next we can start using Mio. The following is quick introduction using TcpListener and TcpStream. Note that features = ["os-poll", "net"] must be specified for this example.

use std::error::Error;

use mio::net::{TcpListener, TcpStream};
use mio::{Events, Interest, Poll, Token};

// Some tokens to allow us to identify which event is for which socket.
const SERVER: Token = Token(0);
const CLIENT: Token = Token(1);

fn main() -> Result<(), Box<dyn Error>> {
    // Create a poll instance.
    let mut poll = Poll::new()?;
    // Create storage for events.
    let mut events = Events::with_capacity(128);

    // Setup the server socket.
    let addr = "127.0.0.1:13265".parse()?;
    let mut server = TcpListener::bind(addr)?;
    // Start listening for incoming connections.
    poll.registry()
        .register(&mut server, SERVER, Interest::READABLE)?;

    // Setup the client socket.
    let mut client = TcpStream::connect(addr)?;
    // Register the socket.
    poll.registry()
        .register(&mut client, CLIENT, Interest::READABLE | Interest::WRITABLE)?;

    // Start an event loop.
    loop {
        // Poll Mio for events, blocking until we get an event.
        poll.poll(&mut events, None)?;

        // Process each event.
        for event in events.iter() {
            // We can use the token we previously provided to `register` to
            // determine for which socket the event is.
            match event.token() {
                SERVER => {
                    // If this is an event for the server, it means a connection
                    // is ready to be accepted.
                    //
                    // Accept the connection and drop it immediately. This will
                    // close the socket and notify the client of the EOF.
                    let connection = server.accept();
                    drop(connection);
                }
                CLIENT => {
                    if event.is_writable() {
                        // We can (likely) write to the socket without blocking.
                    }

                    if event.is_readable() {
                        // We can (likely) read from the socket without blocking.
                    }

                    // Since the server just shuts down the connection, let's
                    // just exit from our event loop.
                    return Ok(());
                }
                // We don't expect any events with tokens other than those we provided.
                _ => unreachable!(),
            }
        }
    }
}

Features

• Non-blocking TCP, UDP
• I/O event queue backed by epoll, kqueue, and IOCP
• Zero allocations at runtime
• Platform specific extensions

View on Github

3 - Rust-lang/futures-rs:

Zero-cost futures in Rust.

futures-rs is a library providing the foundations for asynchronous programming in Rust. It includes key trait definitions like Stream, as well as utilities like join!, select!, and various futures combinator methods which enable expressive asynchronous control flow.

Usage

Add this to your Cargo.toml:

[dependencies]
futures = "0.3"

The current futures requires Rust 1.45 or later.

Feature std

Futures-rs works without the standard library, such as in bare metal environments. However, it has a significantly reduced API surface. To use futures-rs in a #[no_std] environment, use:

[dependencies]
futures = { version = "0.3", default-features = false }

View on Github

4 - TeaEntityLab/fpRust:

Monad/MonadIO, Handler, Coroutine/doNotation, Functional Programming features for Rust.

Why

I love functional programming, Rx-style coding.

However it's hard to implement them in Rust, and there're few libraries to achieve parts of them.

Thus I implemented fpRust. I hope you would like it :)

Features

MonadIO, Rx-like (fp_rust::monadio::MonadIO)

• map/fmap/subscribe
• async/sync
• Support Future (to_future()) with *feature: for_futures

Publisher (fp_rust::publisher::Publisher)

• Support Stream implementation(subscribe_as_stream()) with *feature: for_futures

Fp functions (fp_rust::fp)

• compose!(), pipe!()
• map!(), reduce!(), filter!(), foldl!(), foldr!()
• contains!(), reverse!()

Async (fp_rust::sync & fp_rust::handler::HandlerThread)

• simple BlockingQueue (inspired by Java BlockingQueue, implemented by built-in std::sync::mpsc::channel)
• HandlerThread (inspired by Android Handler, implemented by built-in std::thread)
• WillAsync (inspired by Java Future)
  • Support as a Future with *feature: for_futures
• CountDownLatch (inspired by Java CountDownLatch, implemented by built-in std::sync::Mutex)
  • Support as a Future with *feature: for_futures

Cor (fp_rust::cor::Cor)

• PythonicGenerator-like Coroutine
• yield/yieldFrom
• async/sync

Actor (fp_rust::actor::ActorAsync)

• Pure simple Actor model(receive/send/spawn)
• Context for keeping internal states
• Able to communicate with Parent/Children Actors

DoNotation (fp_rust::cor::Cor)

• Haskell DoNotation-like, macro

* Pattern matching

Usage

MonadIO (RxObserver-like)

Example:

extern crate fp_rust;

use std::{
    thread,
    time,
    sync::{
        Arc,
        Mutex,
        Condvar,
    }
};

use fp_rust::handler::{
    Handler,
    HandlerThread,
};
use fp_rust::common::SubscriptionFunc;
use fp_rust::monadio::{
    MonadIO,
    of,
};
use fp_rust::sync::CountDownLatch;

// fmap & map (sync)
let mut _subscription = Arc::new(SubscriptionFunc::new(move |x: Arc<u16>| {
    println!("monadio_sync {:?}", x); // monadio_sync 36
    assert_eq!(36, *Arc::make_mut(&mut x.clone()));
}));
let subscription = _subscription.clone();
let monadio_sync = MonadIO::just(1)
    .fmap(|x| MonadIO::new(move || x * 4))
    .map(|x| x * 3)
    .map(|x| x * 3);
monadio_sync.subscribe(subscription);

// fmap & map (async)
let mut _handler_observe_on = HandlerThread::new_with_mutex();
let mut _handler_subscribe_on = HandlerThread::new_with_mutex();
let monadio_async = MonadIO::new_with_handlers(
    || {
        println!("In string");
        String::from("ok")
    },
    Some(_handler_observe_on.clone()),
    Some(_handler_subscribe_on.clone()),
);

let latch = CountDownLatch::new(1);
let latch2 = latch.clone();

thread::sleep(time::Duration::from_millis(1));

let subscription = Arc::new(SubscriptionFunc::new(move |x: Arc<String>| {
    println!("monadio_async {:?}", x); // monadio_async ok

    latch2.countdown(); // Unlock here
}));
monadio_async.subscribe(subscription);
monadio_async.subscribe(Arc::new(SubscriptionFunc::new(move |x: Arc<String>| {
    println!("monadio_async sub2 {:?}", x); // monadio_async sub2 ok
})));
{
    let mut handler_observe_on = _handler_observe_on.lock().unwrap();
    let mut handler_subscribe_on = _handler_subscribe_on.lock().unwrap();

    println!("hh2");
    handler_observe_on.start();
    handler_subscribe_on.start();
    println!("hh2 running");

    handler_observe_on.post(RawFunc::new(move || {}));
    handler_observe_on.post(RawFunc::new(move || {}));
    handler_observe_on.post(RawFunc::new(move || {}));
    handler_observe_on.post(RawFunc::new(move || {}));
    handler_observe_on.post(RawFunc::new(move || {}));
}
thread::sleep(time::Duration::from_millis(1));

// Waiting for being unlcoked
latch.clone().wait();

View on Github

5 - Xudong-Huang/may:

Rust stackful coroutine library.

May is a high-performance library for programming stackful coroutines with which you can easily develop and maintain massive concurrent programs. It can be thought as the Rust version of the popular Goroutine.

Features

• The stackful coroutine implementation is based on generator;
• Support schedule on a configurable number of threads for multi-core systems;
• Support coroutine version of a local storage (CLS);
• Support efficient asynchronous network I/O;
• Support efficient timer management;
• Support standard synchronization primitives, a semaphore, an MPMC channel, etc;
• Support cancellation of coroutines;
• Support graceful panic handling that will not affect other coroutines;
• Support scoped coroutine creation;
• Support general selection for all the coroutine API;
• All the coroutine API are compatible with the standard library semantics;
• All the coroutine API can be safely called in multi-threaded context;
• Both stable, beta, and nightly channels are supported;
• x86_64 GNU/Linux, x86_64 Windows, x86_64 Mac, AArch64 Linux OS are supported.

---

Usage

A naive echo server implemented with May:

#[macro_use]
extern crate may;

use may::net::TcpListener;
use std::io::{Read, Write};

fn main() {
    let listener = TcpListener::bind("127.0.0.1:8000").unwrap();
    while let Ok((mut stream, _)) = listener.accept() {
        go!(move || {
            let mut buf = vec![0; 1024 * 16]; // alloc in heap!
            while let Ok(n) = stream.read(&mut buf) {
                if n == 0 {
                    break;
                }
                stream.write_all(&buf[0..n]).unwrap();
            }
        });
    }
}

View on Github

6 - Zonyitoo/coio-rs:

A coroutine I/O library with a working-stealing scheduler.

Feature

• Non-blocking I/O
• Work-stealing coroutine scheduling
• Asynchronous computing APIs

Usage

Note: You must use Nightly Rust to build this Project.

[dependencies.coio]
git = "https://github.com/zonyitoo/coio-rs.git"

Basic Coroutines

extern crate coio;

use coio::Scheduler;

fn main() {
    Scheduler::new()
        .run(|| {
            for _ in 0..10 {
                println!("Heil Hydra");
                Scheduler::sched(); // Yields the current coroutine
            }
        })
        .unwrap();
}

TCP Echo Server

extern crate coio;

use std::io::{Read, Write};

use coio::net::TcpListener;
use coio::{spawn, Scheduler};

fn main() {
    // Spawn a coroutine for accepting new connections
    Scheduler::new().with_workers(4).run(move|| {
        let acceptor = TcpListener::bind("127.0.0.1:8080").unwrap();
        println!("Waiting for connection ...");

        for stream in acceptor.incoming() {
            let (mut stream, addr) = stream.unwrap();

            println!("Got connection from {:?}", addr);

            // Spawn a new coroutine to handle the connection
            spawn(move|| {
                let mut buf = [0; 1024];

                loop {
                    match stream.read(&mut buf) {
                        Ok(0) => {
                            println!("EOF");
                            break;
                        },
                        Ok(len) => {
                            println!("Read {} bytes, echo back", len);
                            stream.write_all(&buf[0..len]).unwrap();
                        },
                        Err(err) => {
                            println!("Error occurs: {:?}", err);
                            break;
                        }
                    }
                }

                println!("Client closed");
            });
        }
    }).unwrap();
}

View on Github

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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_quality、car_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break、loop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 - 1。color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 

Serde Rust: Serialization Framework for Rust

Serde

*Serde is a framework for serializing and deserializing Rust data structures efficiently and generically.*

You may be looking for:

• An overview of Serde
• Data formats supported by Serde
• Setting up #[derive(Serialize, Deserialize)]
• Examples
• API documentation
• Release notes

Serde in action

Click to show Cargo.toml. Run this code in the playground.

[dependencies]

# The core APIs, including the Serialize and Deserialize traits. Always
# required when using Serde. The "derive" feature is only required when
# using #[derive(Serialize, Deserialize)] to make Serde work with structs
# and enums defined in your crate.
serde = { version = "1.0", features = ["derive"] }

# Each data format lives in its own crate; the sample code below uses JSON
# but you may be using a different one.
serde_json = "1.0"

 

use serde::{Serialize, Deserialize};

#[derive(Serialize, Deserialize, Debug)]
struct Point {
    x: i32,
    y: i32,
}

fn main() {
    let point = Point { x: 1, y: 2 };

    // Convert the Point to a JSON string.
    let serialized = serde_json::to_string(&point).unwrap();

    // Prints serialized = {"x":1,"y":2}
    println!("serialized = {}", serialized);

    // Convert the JSON string back to a Point.
    let deserialized: Point = serde_json::from_str(&serialized).unwrap();

    // Prints deserialized = Point { x: 1, y: 2 }
    println!("deserialized = {:?}", deserialized);
}

Getting help

Serde is one of the most widely used Rust libraries so any place that Rustaceans congregate will be able to help you out. For chat, consider trying the #rust-questions or #rust-beginners channels of the unofficial community Discord (invite: https://discord.gg/rust-lang-community), the #rust-usage or #beginners channels of the official Rust Project Discord (invite: https://discord.gg/rust-lang), or the #general stream in Zulip. For asynchronous, consider the [rust] tag on StackOverflow, the /r/rust subreddit which has a pinned weekly easy questions post, or the Rust Discourse forum. It's acceptable to file a support issue in this repo but they tend not to get as many eyes as any of the above and may get closed without a response after some time.

Download Details:
Author: serde-rs
Source Code: https://github.com/serde-rs/serde
License: View license

#rust  #rustlang 

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 

Serde JSON: JSON Support for Serde Framework

Serde JSON

Serde is a framework for serializing and deserializing Rust data structures efficiently and generically.

[dependencies]
serde_json = "1.0"

You may be looking for:

• JSON API documentation
• Serde API documentation
• Detailed documentation about Serde
• Setting up #[derive(Serialize, Deserialize)]
• Release notes

JSON is a ubiquitous open-standard format that uses human-readable text to transmit data objects consisting of key-value pairs.

{
    "name": "John Doe",
    "age": 43,
    "address": {
        "street": "10 Downing Street",
        "city": "London"
    },
    "phones": [
        "+44 1234567",
        "+44 2345678"
    ]
}

There are three common ways that you might find yourself needing to work with JSON data in Rust.

• As text data. An unprocessed string of JSON data that you receive on an HTTP endpoint, read from a file, or prepare to send to a remote server.
• As an untyped or loosely typed representation. Maybe you want to check that some JSON data is valid before passing it on, but without knowing the structure of what it contains. Or you want to do very basic manipulations like insert a key in a particular spot.
• As a strongly typed Rust data structure. When you expect all or most of your data to conform to a particular structure and want to get real work done without JSON's loosey-goosey nature tripping you up.

Serde JSON provides efficient, flexible, safe ways of converting data between each of these representations.

Operating on untyped JSON values

Any valid JSON data can be manipulated in the following recursive enum representation. This data structure is serde_json::Value.

enum Value {
    Null,
    Bool(bool),
    Number(Number),
    String(String),
    Array(Vec<Value>),
    Object(Map<String, Value>),
}

A string of JSON data can be parsed into a serde_json::Value by the serde_json::from_str function. There is also from_slice for parsing from a byte slice &[u8] and from_reader for parsing from any io::Read like a File or a TCP stream.

use serde_json::{Result, Value};

fn untyped_example() -> Result<()> {
    // Some JSON input data as a &str. Maybe this comes from the user.
    let data = r#"
        {
            "name": "John Doe",
            "age": 43,
            "phones": [
                "+44 1234567",
                "+44 2345678"
            ]
        }"#;

    // Parse the string of data into serde_json::Value.
    let v: Value = serde_json::from_str(data)?;

    // Access parts of the data by indexing with square brackets.
    println!("Please call {} at the number {}", v["name"], v["phones"][0]);

    Ok(())
}

The result of square bracket indexing like v["name"] is a borrow of the data at that index, so the type is &Value. A JSON map can be indexed with string keys, while a JSON array can be indexed with integer keys. If the type of the data is not right for the type with which it is being indexed, or if a map does not contain the key being indexed, or if the index into a vector is out of bounds, the returned element is Value::Null.

When a Value is printed, it is printed as a JSON string. So in the code above, the output looks like Please call "John Doe" at the number "+44 1234567". The quotation marks appear because v["name"] is a &Value containing a JSON string and its JSON representation is "John Doe". Printing as a plain string without quotation marks involves converting from a JSON string to a Rust string with as_str() or avoiding the use of Value as described in the following section.

The Value representation is sufficient for very basic tasks but can be tedious to work with for anything more significant. Error handling is verbose to implement correctly, for example imagine trying to detect the presence of unrecognized fields in the input data. The compiler is powerless to help you when you make a mistake, for example imagine typoing v["name"] as v["nmae"] in one of the dozens of places it is used in your code.

Parsing JSON as strongly typed data structures

Serde provides a powerful way of mapping JSON data into Rust data structures largely automatically.

use serde::{Deserialize, Serialize};
use serde_json::Result;

#[derive(Serialize, Deserialize)]
struct Person {
    name: String,
    age: u8,
    phones: Vec<String>,
}

fn typed_example() -> Result<()> {
    // Some JSON input data as a &str. Maybe this comes from the user.
    let data = r#"
        {
            "name": "John Doe",
            "age": 43,
            "phones": [
                "+44 1234567",
                "+44 2345678"
            ]
        }"#;

    // Parse the string of data into a Person object. This is exactly the
    // same function as the one that produced serde_json::Value above, but
    // now we are asking it for a Person as output.
    let p: Person = serde_json::from_str(data)?;

    // Do things just like with any other Rust data structure.
    println!("Please call {} at the number {}", p.name, p.phones[0]);

    Ok(())
}

This is the same serde_json::from_str function as before, but this time we assign the return value to a variable of type Person so Serde will automatically interpret the input data as a Person and produce informative error messages if the layout does not conform to what a Person is expected to look like.

Any type that implements Serde's Deserialize trait can be deserialized this way. This includes built-in Rust standard library types like Vec<T> and HashMap<K, V>, as well as any structs or enums annotated with #[derive(Deserialize)].

Once we have p of type Person, our IDE and the Rust compiler can help us use it correctly like they do for any other Rust code. The IDE can autocomplete field names to prevent typos, which was impossible in the serde_json::Value representation. And the Rust compiler can check that when we write p.phones[0], then p.phones is guaranteed to be a Vec<String> so indexing into it makes sense and produces a String.

The necessary setup for using Serde's derive macros is explained on the Using derive page of the Serde site.

Constructing JSON values

Serde JSON provides a json! macro to build serde_json::Value objects with very natural JSON syntax.

use serde_json::json;

fn main() {
    // The type of `john` is `serde_json::Value`
    let john = json!({
        "name": "John Doe",
        "age": 43,
        "phones": [
            "+44 1234567",
            "+44 2345678"
        ]
    });

    println!("first phone number: {}", john["phones"][0]);

    // Convert to a string of JSON and print it out
    println!("{}", john.to_string());
}

The Value::to_string() function converts a serde_json::Value into a String of JSON text.

One neat thing about the json! macro is that variables and expressions can be interpolated directly into the JSON value as you are building it. Serde will check at compile time that the value you are interpolating is able to be represented as JSON.

let full_name = "John Doe";
let age_last_year = 42;

// The type of `john` is `serde_json::Value`
let john = json!({
    "name": full_name,
    "age": age_last_year + 1,
    "phones": [
        format!("+44 {}", random_phone())
    ]
});

This is amazingly convenient, but we have the problem we had before with Value: the IDE and Rust compiler cannot help us if we get it wrong. Serde JSON provides a better way of serializing strongly-typed data structures into JSON text.

Creating JSON by serializing data structures

A data structure can be converted to a JSON string by serde_json::to_string. There is also serde_json::to_vec which serializes to a Vec<u8> and serde_json::to_writer which serializes to any io::Write such as a File or a TCP stream.

use serde::{Deserialize, Serialize};
use serde_json::Result;

#[derive(Serialize, Deserialize)]
struct Address {
    street: String,
    city: String,
}

fn print_an_address() -> Result<()> {
    // Some data structure.
    let address = Address {
        street: "10 Downing Street".to_owned(),
        city: "London".to_owned(),
    };

    // Serialize it to a JSON string.
    let j = serde_json::to_string(&address)?;

    // Print, write to a file, or send to an HTTP server.
    println!("{}", j);

    Ok(())
}

Any type that implements Serde's Serialize trait can be serialized this way. This includes built-in Rust standard library types like Vec<T> and HashMap<K, V>, as well as any structs or enums annotated with #[derive(Serialize)].

Performance

It is fast. You should expect in the ballpark of 500 to 1000 megabytes per second deserialization and 600 to 900 megabytes per second serialization, depending on the characteristics of your data. This is competitive with the fastest C and C++ JSON libraries or even 30% faster for many use cases. Benchmarks live in the serde-rs/json-benchmark repo.

Getting help

Serde is one of the most widely used Rust libraries, so any place that Rustaceans congregate will be able to help you out. For chat, consider trying the #rust-questions or #rust-beginners channels of the unofficial community Discord (invite: https://discord.gg/rust-lang-community), the #rust-usage or #beginners channels of the official Rust Project Discord (invite: https://discord.gg/rust-lang), or the #general stream in Zulip. For asynchronous, consider the [rust] tag on StackOverflow, the /r/rust subreddit which has a pinned weekly easy questions post, or the Rust Discourse forum. It's acceptable to file a support issue in this repo, but they tend not to get as many eyes as any of the above and may get closed without a response after some time.

No-std support

As long as there is a memory allocator, it is possible to use serde_json without the rest of the Rust standard library. This is supported on Rust 1.36+. Disable the default "std" feature and enable the "alloc" feature:

[dependencies]
serde_json = { version = "1.0", default-features = false, features = ["alloc"] }

For JSON support in Serde without a memory allocator, please see the serde-json-core crate.

Link: https://crates.io/crates/serde_json

#rust  #rustlang  #encode   #json