Vaadin Grid renderers: customize cells and show a details row (Fusion)

In this video, Marcus Hellberg teaches you how to use renderers for customizing cell contents in a Vaadin Grid, and how to show expand a details row for selected grid items.

0:00 - Intro
0:16 - App walkthrough
0:52 - Using a renderer to customize cells in a vaadin-grid
4:22 - Showing row details with a row details renderer
6:16 - How to handle grid selection and expanding details
9:06 - Outro

Source: https://github.com/marcushellberg/vaadin-grid-renderers

Subscribe: https://www.youtube.com/channel/UCsGakFIbOsj-fgPFLf1QlQA

#vaadin #web-development

What is GEEK

Buddha Community

Vaadin Grid renderers: customize cells and show a details row (Fusion)

Callum Slater

1653465344

PySpark Cheat Sheet: Spark DataFrames in Python

This PySpark SQL cheat sheet is your handy companion to Apache Spark DataFrames in Python and includes code samples.

You'll probably already know about Apache Spark, the fast, general and open-source engine for big data processing; It has built-in modules for streaming, SQL, machine learning and graph processing. Spark allows you to speed analytic applications up to 100 times faster compared to other technologies on the market today. Interfacing Spark with Python is easy with PySpark: this Spark Python API exposes the Spark programming model to Python.

Now, it's time to tackle the Spark SQL module, which is meant for structured data processing, and the DataFrame API, which is not only available in Python, but also in Scala, Java, and R.

Without further ado, here's the cheat sheet:

PySpark SQL cheat sheet

This PySpark SQL cheat sheet covers the basics of working with the Apache Spark DataFrames in Python: from initializing the SparkSession to creating DataFrames, inspecting the data, handling duplicate values, querying, adding, updating or removing columns, grouping, filtering or sorting data. You'll also see that this cheat sheet also on how to run SQL Queries programmatically, how to save your data to parquet and JSON files, and how to stop your SparkSession.

Spark SGlL is Apache Spark's module for working with structured data.

Initializing SparkSession

A SparkSession can be used create DataFrame, register DataFrame as tables, execute SGL over tables, cache tables, and read parquet files.

>>> from pyspark.sql import SparkSession
>>> spark a SparkSession \
     .builder\
     .appName("Python Spark SQL basic example") \
     .config("spark.some.config.option", "some-value") \
     .getOrCreate()

Creating DataFrames

Fromm RDDs

>>> from pyspark.sql.types import*

Infer Schema

>>> sc = spark.sparkContext
>>> lines = sc.textFile(''people.txt'')
>>> parts = lines.map(lambda l: l.split(","))
>>> people = parts.map(lambda p: Row(nameap[0],ageaint(p[l])))
>>> peopledf = spark.createDataFrame(people)

Specify Schema

>>> people = parts.map(lambda p: Row(name=p[0],
               age=int(p[1].strip())))
>>>  schemaString = "name age"
>>> fields = [StructField(field_name, StringType(), True) for field_name in schemaString.split()]
>>> schema = StructType(fields)
>>> spark.createDataFrame(people, schema).show()

From Spark Data Sources
JSON

>>>  df = spark.read.json("customer.json")
>>> df.show()

>>>  df2 = spark.read.load("people.json", format="json")

Parquet files

>>> df3 = spark.read.load("users.parquet")

TXT files

>>> df4 = spark.read.text("people.txt")

Filter

#Filter entries of age, only keep those records of which the values are >24
>>> df.filter(df["age"]>24).show()

Duplicate Values

>>> df = df.dropDuplicates()

Queries

>>> from pyspark.sql import functions as F

Select

>>> df.select("firstName").show() #Show all entries in firstName column
>>> df.select("firstName","lastName") \
      .show()
>>> df.select("firstName", #Show all entries in firstName, age and type
              "age",
              explode("phoneNumber") \
              .alias("contactInfo")) \
      .select("contactInfo.type",
              "firstName",
              "age") \
      .show()
>>> df.select(df["firstName"],df["age"]+ 1) #Show all entries in firstName and age, .show() add 1 to the entries of age
>>> df.select(df['age'] > 24).show() #Show all entries where age >24

When

>>> df.select("firstName", #Show firstName and 0 or 1 depending on age >30
               F.when(df.age > 30, 1) \
              .otherwise(0)) \
      .show()
>>> df[df.firstName.isin("Jane","Boris")] #Show firstName if in the given options
.collect()

>>> df.select("firstName", #Show firstName, and lastName is TRUE if lastName is like Smith
              df.lastName.like("Smith")) \
     .show()

Startswith - Endswith

>>> df.select("firstName", #Show firstName, and TRUE if lastName starts with Sm
              df.lastName \
                .startswith("Sm")) \
      .show()
>>> df.select(df.lastName.endswith("th"))\ #Show last names ending in th
      .show()

Substring

>>> df.select(df.firstName.substr(1, 3) \ #Return substrings of firstName
                          .alias("name")) \
        .collect()

Between

>>> df.select(df.age.between(22, 24)) \ #Show age: values are TRUE if between 22 and 24
          .show()

Add, Update & Remove Columns

Adding Columns

 >>> df = df.withColumn('city',df.address.city) \
            .withColumn('postalCode',df.address.postalCode) \
            .withColumn('state',df.address.state) \
            .withColumn('streetAddress',df.address.streetAddress) \
            .withColumn('telePhoneNumber', explode(df.phoneNumber.number)) \
            .withColumn('telePhoneType', explode(df.phoneNumber.type))

Updating Columns

>>> df = df.withColumnRenamed('telePhoneNumber', 'phoneNumber')

Removing Columns

  >>> df = df.drop("address", "phoneNumber")
 >>> df = df.drop(df.address).drop(df.phoneNumber)

Missing & Replacing Values

>>> df.na.fill(50).show() #Replace null values
 >>> df.na.drop().show() #Return new df omitting rows with null values
 >>> df.na \ #Return new df replacing one value with another
       .replace(10, 20) \
       .show()

GroupBy

>>> df.groupBy("age")\ #Group by age, count the members in the groups
      .count() \
      .show()

Sort

>>> peopledf.sort(peopledf.age.desc()).collect()
>>> df.sort("age", ascending=False).collect()
>>> df.orderBy(["age","city"],ascending=[0,1])\
     .collect()

Repartitioning

>>> df.repartition(10)\ #df with 10 partitions
      .rdd \
      .getNumPartitions()
>>> df.coalesce(1).rdd.getNumPartitions() #df with 1 partition

Running Queries Programmatically

Registering DataFrames as Views

>>> peopledf.createGlobalTempView("people")
>>> df.createTempView("customer")
>>> df.createOrReplaceTempView("customer")

Query Views

>>> df5 = spark.sql("SELECT * FROM customer").show()
>>> peopledf2 = spark.sql("SELECT * FROM global_temp.people")\
               .show()

Inspect Data

>>> df.dtypes #Return df column names and data types
>>> df.show() #Display the content of df
>>> df.head() #Return first n rows
>>> df.first() #Return first row
>>> df.take(2) #Return the first n rows >>> df.schema Return the schema of df
>>> df.describe().show() #Compute summary statistics >>> df.columns Return the columns of df
>>> df.count() #Count the number of rows in df
>>> df.distinct().count() #Count the number of distinct rows in df
>>> df.printSchema() #Print the schema of df
>>> df.explain() #Print the (logical and physical) plans

Output

Data Structures

 >>> rdd1 = df.rdd #Convert df into an RDD
 >>> df.toJSON().first() #Convert df into a RDD of string
 >>> df.toPandas() #Return the contents of df as Pandas DataFrame

Write & Save to Files

>>> df.select("firstName", "city")\
       .write \
       .save("nameAndCity.parquet")
 >>> df.select("firstName", "age") \
       .write \
       .save("namesAndAges.json",format="json")

Stopping SparkSession

>>> spark.stop()

Have this Cheat Sheet at your fingertips

Original article source at https://www.datacamp.com

#pyspark #cheatsheet #spark #dataframes #python #bigdata

Robert E. Hilton

1642496884

How to Create a Responsive Dropdown Menu Bar with Search Field using HTML & CSS

In this guide you’ll learn how to create a Responsive Dropdown Menu Bar with Search Field using only HTML & CSS.

To create a responsive dropdown menu bar with search field using only HTML & CSS . First, you need to create two Files one HTML File and another one is CSS File.

1: First, create an HTML file with the name of index.html

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>Dropdown Menu with Search Box | Codequs</title>
  <link rel="stylesheet" href="style.css">
  <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/5.15.3/css/all.min.css"/>
</head>
<body>
  <div class="wrapper">
    <nav>
      <input type="checkbox" id="show-search">
      <input type="checkbox" id="show-menu">
      <label for="show-menu" class="menu-icon"><i class="fas fa-bars"></i></label>
      <div class="content">
      <div class="logo"><a href="#">CodingNepal</a></div>
        <ul class="links">
          <li><a href="#">Home</a></li>
          <li><a href="#">About</a></li>
          <li>
            <a href="#" class="desktop-link">Features</a>
            <input type="checkbox" id="show-features">
            <label for="show-features">Features</label>
            <ul>
              <li><a href="#">Drop Menu 1</a></li>
              <li><a href="#">Drop Menu 2</a></li>
              <li><a href="#">Drop Menu 3</a></li>
              <li><a href="#">Drop Menu 4</a></li>
            </ul>
          </li>
          <li>
            <a href="#" class="desktop-link">Services</a>
            <input type="checkbox" id="show-services">
            <label for="show-services">Services</label>
            <ul>
              <li><a href="#">Drop Menu 1</a></li>
              <li><a href="#">Drop Menu 2</a></li>
              <li><a href="#">Drop Menu 3</a></li>
              <li>
                <a href="#" class="desktop-link">More Items</a>
                <input type="checkbox" id="show-items">
                <label for="show-items">More Items</label>
                <ul>
                  <li><a href="#">Sub Menu 1</a></li>
                  <li><a href="#">Sub Menu 2</a></li>
                  <li><a href="#">Sub Menu 3</a></li>
                </ul>
              </li>
            </ul>
          </li>
          <li><a href="#">Feedback</a></li>
        </ul>
      </div>
      <label for="show-search" class="search-icon"><i class="fas fa-search"></i></label>
      <form action="#" class="search-box">
        <input type="text" placeholder="Type Something to Search..." required>
        <button type="submit" class="go-icon"><i class="fas fa-long-arrow-alt-right"></i></button>
      </form>
    </nav>
  </div>
  <div class="dummy-text">
    <h2>Responsive Dropdown Menu Bar with Searchbox</h2>
    <h2>using only HTML & CSS - Flexbox</h2>
  </div>
</body>
</html>

2: Second, create a CSS file with the name of style.css

@import url('https://fonts.googleapis.com/css2?family=Poppins:wght@200;300;400;500;600;700&display=swap');
*{
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  text-decoration: none;
  font-family: 'Poppins', sans-serif;
}
.wrapper{
  background: #171c24;
  position: fixed;
  width: 100%;
}
.wrapper nav{
  position: relative;
  display: flex;
  max-width: calc(100% - 200px);
  margin: 0 auto;
  height: 70px;
  align-items: center;
  justify-content: space-between;
}
nav .content{
  display: flex;
  align-items: center;
}
nav .content .links{
  margin-left: 80px;
  display: flex;
}
.content .logo a{
  color: #fff;
  font-size: 30px;
  font-weight: 600;
}
.content .links li{
  list-style: none;
  line-height: 70px;
}
.content .links li a,
.content .links li label{
  color: #fff;
  font-size: 18px;
  font-weight: 500;
  padding: 9px 17px;
  border-radius: 5px;
  transition: all 0.3s ease;
}
.content .links li label{
  display: none;
}
.content .links li a:hover,
.content .links li label:hover{
  background: #323c4e;
}
.wrapper .search-icon,
.wrapper .menu-icon{
  color: #fff;
  font-size: 18px;
  cursor: pointer;
  line-height: 70px;
  width: 70px;
  text-align: center;
}
.wrapper .menu-icon{
  display: none;
}
.wrapper #show-search:checked ~ .search-icon i::before{
  content: "\f00d";
}
.wrapper .search-box{
  position: absolute;
  height: 100%;
  max-width: calc(100% - 50px);
  width: 100%;
  opacity: 0;
  pointer-events: none;
  transition: all 0.3s ease;
}
.wrapper #show-search:checked ~ .search-box{
  opacity: 1;
  pointer-events: auto;
}
.search-box input{
  width: 100%;
  height: 100%;
  border: none;
  outline: none;
  font-size: 17px;
  color: #fff;
  background: #171c24;
  padding: 0 100px 0 15px;
}
.search-box input::placeholder{
  color: #f2f2f2;
}
.search-box .go-icon{
  position: absolute;
  right: 10px;
  top: 50%;
  transform: translateY(-50%);
  line-height: 60px;
  width: 70px;
  background: #171c24;
  border: none;
  outline: none;
  color: #fff;
  font-size: 20px;
  cursor: pointer;
}
.wrapper input[type="checkbox"]{
  display: none;
}
/* Dropdown Menu code start */
.content .links ul{
  position: absolute;
  background: #171c24;
  top: 80px;
  z-index: -1;
  opacity: 0;
  visibility: hidden;
}
.content .links li:hover > ul{
  top: 70px;
  opacity: 1;
  visibility: visible;
  transition: all 0.3s ease;
}
.content .links ul li a{
  display: block;
  width: 100%;
  line-height: 30px;
  border-radius: 0px!important;
}
.content .links ul ul{
  position: absolute;
  top: 0;
  right: calc(-100% + 8px);
}
.content .links ul li{
  position: relative;
}
.content .links ul li:hover ul{
  top: 0;
}
/* Responsive code start */
@media screen and (max-width: 1250px){
  .wrapper nav{
    max-width: 100%;
    padding: 0 20px;
  }
  nav .content .links{
    margin-left: 30px;
  }
  .content .links li a{
    padding: 8px 13px;
  }
  .wrapper .search-box{
    max-width: calc(100% - 100px);
  }
  .wrapper .search-box input{
    padding: 0 100px 0 15px;
  }
}
@media screen and (max-width: 900px){
  .wrapper .menu-icon{
    display: block;
  }
  .wrapper #show-menu:checked ~ .menu-icon i::before{
    content: "\f00d";
  }
  nav .content .links{
    display: block;
    position: fixed;
    background: #14181f;
    height: 100%;
    width: 100%;
    top: 70px;
    left: -100%;
    margin-left: 0;
    max-width: 350px;
    overflow-y: auto;
    padding-bottom: 100px;
    transition: all 0.3s ease;
  }
  nav #show-menu:checked ~ .content .links{
    left: 0%;
  }
  .content .links li{
    margin: 15px 20px;
  }
  .content .links li a,
  .content .links li label{
    line-height: 40px;
    font-size: 20px;
    display: block;
    padding: 8px 18px;
    cursor: pointer;
  }
  .content .links li a.desktop-link{
    display: none;
  }
  /* dropdown responsive code start */
  .content .links ul,
  .content .links ul ul{
    position: static;
    opacity: 1;
    visibility: visible;
    background: none;
    max-height: 0px;
    overflow: hidden;
  }
  .content .links #show-features:checked ~ ul,
  .content .links #show-services:checked ~ ul,
  .content .links #show-items:checked ~ ul{
    max-height: 100vh;
  }
  .content .links ul li{
    margin: 7px 20px;
  }
  .content .links ul li a{
    font-size: 18px;
    line-height: 30px;
    border-radius: 5px!important;
  }
}
@media screen and (max-width: 400px){
  .wrapper nav{
    padding: 0 10px;
  }
  .content .logo a{
    font-size: 27px;
  }
  .wrapper .search-box{
    max-width: calc(100% - 70px);
  }
  .wrapper .search-box .go-icon{
    width: 30px;
    right: 0;
  }
  .wrapper .search-box input{
    padding-right: 30px;
  }
}
.dummy-text{
  position: absolute;
  top: 50%;
  left: 50%;
  width: 100%;
  z-index: -1;
  padding: 0 20px;
  text-align: center;
  transform: translate(-50%, -50%);
}
.dummy-text h2{
  font-size: 45px;
  margin: 5px 0;
}

Now you’ve successfully created a Responsive Dropdown Menu Bar with Search Field using only HTML & CSS.

Thomas Coper

1611808714

Vaadin Grid renderers: customize cells and show a details row (Fusion)

In this video, Marcus Hellberg teaches you how to use renderers for customizing cell contents in a Vaadin Grid, and how to show expand a details row for selected grid items.

Source: https://github.com/marcushellberg/vaadin-grid-renderers

Subscribe: https://www.youtube.com/channel/UCsGakFIbOsj-fgPFLf1QlQA

#vaadin #web-development

Beth Cooper

1659694200

Easy Activity Tracking for Models, Similar to Github's Public Activity

PublicActivity

public_activity provides easy activity tracking for your ActiveRecord, Mongoid 3 and MongoMapper models in Rails 3 and 4.

Simply put: it can record what happens in your application and gives you the ability to present those recorded activities to users - in a similar way to how GitHub does it.

!! WARNING: README for unreleased version below. !!

You probably don't want to read the docs for this unreleased version 2.0.

For the stable 1.5.X readme see: https://github.com/chaps-io/public_activity/blob/1-5-stable/README.md

About

Here is a simple example showing what this gem is about:

Example usage

Tutorials

Screencast

Ryan Bates made a great screencast describing how to integrate Public Activity.

Tutorial

A great step-by-step guide on implementing activity feeds using public_activity by Ilya Bodrov.

Online demo

You can see an actual application using this gem here: http://public-activity-example.herokuapp.com/feed

The source code of the demo is hosted here: https://github.com/pokonski/activity_blog

Setup

Gem installation

You can install public_activity as you would any other gem:

gem install public_activity

or in your Gemfile:

gem 'public_activity'

Database setup

By default public_activity uses Active Record. If you want to use Mongoid or MongoMapper as your backend, create an initializer file in your Rails application with the corresponding code inside:

For Mongoid:

# config/initializers/public_activity.rb
PublicActivity.configure do |config|
  config.orm = :mongoid
end

For MongoMapper:

# config/initializers/public_activity.rb
PublicActivity.configure do |config|
  config.orm = :mongo_mapper
end

(ActiveRecord only) Create migration for activities and migrate the database (in your Rails project):

rails g public_activity:migration
rake db:migrate

Model configuration

Include PublicActivity::Model and add tracked to the model you want to keep track of:

For ActiveRecord:

class Article < ActiveRecord::Base
  include PublicActivity::Model
  tracked
end

For Mongoid:

class Article
  include Mongoid::Document
  include PublicActivity::Model
  tracked
end

For MongoMapper:

class Article
  include MongoMapper::Document
  include PublicActivity::Model
  tracked
end

And now, by default create/update/destroy activities are recorded in activities table. This is all you need to start recording activities for basic CRUD actions.

Optional: If you don't need #tracked but still want the comfort of #create_activity, you can include only the lightweight Common module instead of Model.

Custom activities

You can trigger custom activities by setting all your required parameters and triggering create_activity on the tracked model, like this:

@article.create_activity key: 'article.commented_on', owner: current_user

See this entry http://rubydoc.info/gems/public_activity/PublicActivity/Common:create_activity for more details.

Displaying activities

To display them you simply query the PublicActivity::Activity model:

# notifications_controller.rb
def index
  @activities = PublicActivity::Activity.all
end

And in your views:

<%= render_activities(@activities) %>

Note: render_activities is an alias for render_activity and does the same.

Layouts

You can also pass options to both activity#render and #render_activity methods, which are passed deeper to the internally used render_partial method. A useful example would be to render activities wrapped in layout, which shares common elements of an activity, like a timestamp, owner's avatar etc:

<%= render_activities(@activities, layout: :activity) %>

The activity will be wrapped with the app/views/layouts/_activity.html.erb layout, in the above example.

Important: please note that layouts for activities are also partials. Hence the _ prefix.

Locals

Sometimes, it's desirable to pass additional local variables to partials. It can be done this way:

<%= render_activity(@activity, locals: {friends: current_user.friends}) %>

Note: Before 1.4.0, one could pass variables directly to the options hash for #render_activity and access it from activity parameters. This functionality is retained in 1.4.0 and later, but the :locals method is preferred, since it prevents bugs from shadowing variables from activity parameters in the database.

Activity views

public_activity looks for views in app/views/public_activity.

For example, if you have an activity with :key set to "activity.user.changed_avatar", the gem will look for a partial in app/views/public_activity/user/_changed_avatar.html.(|erb|haml|slim|something_else).

Hint: the "activity." prefix in :key is completely optional and kept for backwards compatibility, you can skip it in new projects.

If you would like to fallback to a partial, you can utilize the fallback parameter to specify the path of a partial to use when one is missing:

<%= render_activity(@activity, fallback: 'default') %>

When used in this manner, if a partial with the specified :key cannot be located it will use the partial defined in the fallback instead. In the example above this would resolve to public_activity/_default.html.(|erb|haml|slim|something_else).

If a view file does not exist then ActionView::MisingTemplate will be raised. If you wish to fallback to the old behaviour and use an i18n based translation in this situation you can specify a :fallback parameter of text to fallback to this mechanism like such:

<%= render_activity(@activity, fallback: :text) %>

i18n

Translations are used by the #text method, to which you can pass additional options in form of a hash. #render method uses translations when view templates have not been provided. You can render pure i18n strings by passing {display: :i18n} to #render_activity or #render.

Translations should be put in your locale .yml files. To render pure strings from I18n Example structure:

activity:
  article:
    create: 'Article has been created'
    update: 'Someone has edited the article'
    destroy: 'Some user removed an article!'

This structure is valid for activities with keys "activity.article.create" or "article.create". As mentioned before, "activity." part of the key is optional.

Testing

For RSpec you can first disable public_activity and add require helper methods in the rails_helper.rb with:

#rails_helper.rb
require 'public_activity/testing'

PublicActivity.enabled = false

In your specs you can then blockwise decide whether to turn public_activity on or off.

# file_spec.rb
PublicActivity.with_tracking do
  # your test code goes here
end

PublicActivity.without_tracking do
  # your test code goes here
end

Documentation

For more documentation go here

Common examples

Set the Activity's owner to current_user by default

You can set up a default value for :owner by doing this:

Include PublicActivity::StoreController in your ApplicationController like this:

class ApplicationController < ActionController::Base
  include PublicActivity::StoreController
end

Use Proc in :owner attribute for tracked class method in your desired model. For example:

class Article < ActiveRecord::Base
  tracked owner: Proc.new{ |controller, model| controller.current_user }
end

Note: current_user applies to Devise, if you are using a different authentication gem or your own code, change the current_user to a method you use.

Disable tracking for a class or globally

If you need to disable tracking temporarily, for example in tests or db/seeds.rb then you can use PublicActivity.enabled= attribute like below:

# Disable p_a globally
PublicActivity.enabled = false

# Perform some operations that would normally be tracked by p_a:
Article.create(title: 'New article')

# Switch it back on
PublicActivity.enabled = true

You can also disable public_activity for a specific class:

# Disable p_a for Article class
Article.public_activity_off

# p_a will not do anything here:
@article = Article.create(title: 'New article')

# But will be enabled for other classes:
# (creation of the comment will be recorded if you are tracking the Comment class)
@article.comments.create(body: 'some comment!')

# Enable it again for Article:
Article.public_activity_on

Create custom activities

Besides standard, automatic activities created on CRUD actions on your model (deactivatable), you can post your own activities that can be triggered without modifying the tracked model. There are a few ways to do this, as PublicActivity gives three tiers of options to be set.

Instant options

Because every activity needs a key (otherwise: NoKeyProvided is raised), the shortest and minimal way to post an activity is:

@user.create_activity :mood_changed
# the key of the action will be user.mood_changed
@user.create_activity action: :mood_changed # this is exactly the same as above

Besides assigning your key (which is obvious from the code), it will take global options from User class (given in #tracked method during class definition) and overwrite them with instance options (set on @user by #activity method). You can read more about options and how PublicActivity inherits them for you here.

Note the action parameter builds the key like this: "#{model_name}.#{action}". You can read further on options for #create_activity here.

To provide more options, you can do:

@user.create_activity action: 'poke', parameters: {reason: 'bored'}, recipient: @friend, owner: current_user

In this example, we have provided all the things we could for a standard Activity.

Use custom fields on Activity

Besides the few fields that every Activity has (key, owner, recipient, trackable, parameters), you can also set custom fields. This could be very beneficial, as parameters are a serialized hash, which cannot be queried easily from the database. That being said, use custom fields when you know that you will set them very often and search by them (don't forget database indexes :) ).

Set `owner` and `recipient` based on associations

class Comment < ActiveRecord::Base
  include PublicActivity::Model
  tracked owner: :commenter, recipient: :commentee

  belongs_to :commenter, :class_name => "User"
  belongs_to :commentee, :class_name => "User"
end

Resolve parameters from a Symbol or Proc

class Post < ActiveRecord::Base
  include PublicActivity::Model
  tracked only: [:update], parameters: :tracked_values
  
  def tracked_values
   {}.tap do |hash|
     hash[:tags] = tags if tags_changed?
   end
  end
end

Setup

Skip this step if you are using ActiveRecord in Rails 4 or Mongoid

The first step is similar in every ORM available (except mongoid):

PublicActivity::Activity.class_eval do
  attr_accessible :custom_field
end

place this code under config/initializers/public_activity.rb, you have to create it first.

To be able to assign to that field, we need to move it to the mass assignment sanitizer's whitelist.

Migration

If you're using ActiveRecord, you will also need to provide a migration to add the actual field to the Activity. Taken from our tests:

class AddCustomFieldToActivities < ActiveRecord::Migration
  def change
    change_table :activities do |t|
      t.string :custom_field
    end
  end
end

Assigning custom fields

Assigning is done by the same methods that you use for normal parameters: #tracked, #create_activity. You can just pass the name of your custom variable and assign its value. Even better, you can pass it to #tracked to tell us how to harvest your data for custom fields so we can do that for you.

class Article < ActiveRecord::Base
  include PublicActivity::Model
  tracked custom_field: proc {|controller, model| controller.some_helper }
end

Help

If you need help with using public_activity please visit our discussion group and ask a question there:

https://groups.google.com/forum/?fromgroups#!forum/public-activity

Please do not ask general questions in the Github Issues.

Author: public-activity
Source code: https://github.com/public-activity/public_activity
License: MIT license

#ruby #ruby-on-rails

Antwon Lindgren

1659829500

Cells: View Components for Ruby and Rails

Cells

View Components for Ruby and Rails.

Overview

Cells allow you to encapsulate parts of your UI into components into view models. View models, or cells, are simple ruby classes that can render templates.

Nevertheless, a cell gives you more than just a template renderer. They allow proper OOP, polymorphic builders, nesting, view inheritance, using Rails helpers, asset packaging to bundle JS, CSS or images, simple distribution via gems or Rails engines, encapsulated testing, caching, and integrate with Trailblazer.

Full Documentation

Cells is part of the Trailblazer framework. Full documentation is available on the project site.

Cells is completely decoupled from Rails. However, Rails-specific functionality is to be found here.

Rendering Cells

You can render cells anywhere and as many as you want, in views, controllers, composites, mailers, etc.

Rendering a cell in Rails ironically happens via a helper.

<%= cell(:comment, @comment) %>

This boils down to the following invocation, that can be used to render cells in any other Ruby environment.

CommentCell.(@comment).()

You can also pass the cell class in explicitly:

<%= cell(CommentCell, @comment) %>

In Rails you have the same helper API for views and controllers.

class DashboardController < ApplicationController
  def dashboard
    @comments = cell(:comment, collection: Comment.recent)
    @traffic  = cell(:report, TrafficReport.find(1)).()
  end

Usually, you'd pass in one or more objects you want the cell to present. That can be an ActiveRecord model, a ROM instance or any kind of PORO you fancy.

Cell Class

A cell is a light-weight class with one or multiple methods that render views.

class CommentCell < Cell::ViewModel
  property :body
  property :author

  def show
    render
  end

private
  def author_link
    link_to "#{author.email}", author
  end
end

Here, show is the only public method. By calling render it will invoke rendering for the show view.

Logicless Views

Views come packaged with the cell and can be ERB, Haml, or Slim.

<h3>New Comment</h3>
  <%= body %>

By <%= author_link %>

The concept of "helpers" that get strangely copied from modules to the view does not exist in Cells anymore.

Methods called in the view are directly called on the cell instance. You're free to use loops and deciders in views, even instance variables are allowed, but Cells tries to push you gently towards method invocations to access data in the view.

File Structure

In Rails, cells are placed in app/cells or app/concepts/. Every cell has their own directory where it keeps views, assets and code.

app
├── cells
│   ├── comment_cell.rb
│   ├── comment
│   │   ├── show.haml
│   │   ├── list.haml

The discussed show view would reside in app/cells/comment/show.haml. However, you can set any set of view paths you want.

Invocation Styles

In order to make a cell render, you have to call the rendering methods. While you could call the method directly, the preferred way is the call style.

cell(:comment, @song).()       # calls CommentCell#show.
cell(:comment, @song).(:index) # calls CommentCell#index.

The call style respects caching.

Keep in mind that cell(..) really gives you the cell object. In case you want to reuse the cell, need setup logic, etc. that's completely up to you.

Parameters

You can pass in as many parameters as you need. Per convention, this is a hash.

cell(:comment, @song, volume: 99, genre: "Jazz Fusion")

Options can be accessed via the @options instance variable.

Naturally, you may also pass arbitrary options into the call itself. Those will be simple method arguments.

cell(:comment, @song).(:show, volume: 99)

Then, the show method signature changes to def show(options).

Testing

A huge benefit from "all this encapsulation" is that you can easily write tests for your components. The API does not change and everything is exactly as it would be in production.

html = CommentCell.(@comment).()
Capybara.string(html).must_have_css "h3"

It is completely up to you how you test, whether it's RSpec, MiniTest or whatever. All the cell does is return HTML.

In Rails, there's support for TestUnit, MiniTest and RSpec available, along with Capybara integration.

Properties

The cell's model is available via the model reader. You can have automatic readers to the model's fields by using ::property.

class CommentCell < Cell::ViewModel
  property :author # delegates to model.author

  def author_link
    link_to author.name, author
  end
end

HTML Escaping

Cells per default does no HTML escaping, anywhere. Include Escaped to make property readers return escaped strings.

class CommentCell < Cell::ViewModel
  include Escaped

  property :title
end

song.title                 #=> "<script>Dangerous</script>"
Comment::Cell.(song).title #=> &lt;script&gt;Dangerous&lt;/script&gt;

Properties and escaping are documented here.

Installation

Cells runs with any framework.

gem "cells"

For Rails, please use the cells-rails gem. It supports Rails >= 4.0.

gem "cells-rails"

Lower versions of Rails will still run with Cells, but you will get in trouble with the helpers. (Note: we use Cells in production with Rails 3.2 and Haml and it works great.)

Various template engines are supported but need to be added to your Gemfile.

cells-erb
cells-hamlit We strongly recommend using Hamlit as a Haml replacement.
cells-haml Make sure to bundle Haml 4.1: gem "haml", github: "haml/haml", ref: "7c7c169". Use cells-hamlit instead.
cells-slim

gem "cells-erb"

In Rails, this is all you need to do. In other environments, you need to include the respective module into your cells.

class CommentCell < Cell::ViewModel
  include ::Cell::Erb # or Cell::Hamlit, or Cell::Haml, or Cell::Slim
end

Namespaces

Cells can be namespaced as well.

module Admin
  class CommentCell < Cell::ViewModel

Invocation in Rails would happen as follows.

cell("admin/comment", @comment).()

Views will be searched in app/cells/admin/comment per default.

Rails Helper API

Even in a non-Rails environment, Cells provides the Rails view API and allows using all Rails helpers.

You have to include all helper modules into your cell class. You can then use link_to, simple_form_for or whatever you feel like.

class CommentCell < Cell::ViewModel
  include ActionView::Helpers::UrlHelper
  include ActionView::Helpers::CaptureHelper

  def author_link
    content_tag :div, link_to(author.name, author)
  end

As always, you can use helpers in cells and in views.

You might run into problems with wrong escaping or missing URL helpers. This is not Cells' fault but Rails suboptimal way of implementing and interfacing their helpers. Please open the actionview gem helper code and try figuring out the problem yourself before bombarding us with issues because helper xyz doesn't work.

View Paths

In Rails, the view path is automatically set to app/cells/ or app/concepts/. You can append or set view paths by using ::view_paths. Of course, this works in any Ruby environment.

class CommentCell < Cell::ViewModel
  self.view_paths = "lib/views"
end

Asset Packaging

Cells can easily ship with their own JavaScript, CSS and more and be part of Rails' asset pipeline. Bundling assets into a cell allows you to implement super encapsulated widgets that are stand-alone. Asset pipeline is documented here.

Render API

Unlike Rails, the #render method only provides a handful of options you gotta learn.

def show
  render
end

Without options, this will render the state name, e.g. show.erb.

You can provide a view name manually. The following calls are identical.

render :index
render view: :index

If you need locals, pass them to #render.

render locals: {style: "border: solid;"}

Layouts

Every view can be wrapped by a layout. Either pass it when rendering.

render layout: :default

Or configure it on the class-level.

class CommentCell < Cell::ViewModel
  layout :default

The layout is treated as a view and will be searched in the same directories.

Nested Cells

Cells love to render. You can render as many views as you need in a cell state or view.

<%= render :index %>

The #render method really just returns the rendered template string, allowing you all kind of modification.

def show
  render + render(:additional)
end

You can even render other cells within a cell using the exact same API.

def about
  cell(:profile, model.author).()
end

This works both in cell views and on the instance, in states.

View Inheritance

You can not only inherit code across cell classes, but also views. This is extremely helpful if you want to override parts of your UI, only. It's documented here.

Collections

In order to render collections, Cells comes with a shortcut.

comments = Comment.all #=> three comments.
cell(:comment, collection: comments).()

This will invoke cell(:comment, comment).() three times and concatenate the rendered output automatically.

Learn more about collections here.

Builder

Builders allow instantiating different cell classes for different models and options. They introduce polymorphism into cells.

class CommentCell < Cell::ViewModel
  include ::Cell::Builder

  builds do |model, options|
    case model
    when Post; PostCell
    when Comment; CommentCell
    end
  end

The #cell helper takes care of instantiating the right cell class for you.

cell(:comment, Post.find(1)) #=> creates a PostCell.

Learn more about builders here.

Caching

For every cell class you can define caching per state. Without any configuration the cell will run and render the state once. In following invocations, the cached fragment is returned.

class CommentCell < Cell::ViewModel
  cache :show
  # ..
end

The ::cache method will forward options to the caching engine.

cache :show, expires_in: 10.minutes

You can also compute your own cache key, use dynamic keys, cache tags, and conditionals using :if. Caching is documented here and in chapter 8 of the Trailblazer book.

The Book

Cells is part of the Trailblazer project. Please buy my book to support the development and to learn all the cool stuff about Cells. The book discusses many use cases of Cells.

![](https://raw.githubusercontent.com/apotonick/trailblazer/master/doc/trb.jpg)

Basic view models, replacing helpers, and how to structure your view into cell components (chapter 2 and 4).
Advanced Cells API (chapter 4 and 6).
Testing Cells (chapter 4 and 6).
Cells Pagination with AJAX (chapter 6).
View Caching and Expiring (chapter 8).

The book picks up where the README leaves off. Go grab a copy and support us - it talks about object- and view design and covers all aspects of the API.

This is not Cells 3.x!

Temporary note: This is the README and API for Cells 4. Many things have improved. If you want to upgrade, follow this guide. When in trouble, join the Zulip channel.

Author: trailblazer
Source code: https://github.com/trailblazer/cells

#ruby #ruby-on-rails

Vaadin Grid renderers: customize cells and show a details row (Fusion)

What is GEEK

Buddha Community

PySpark Cheat Sheet: Spark DataFrames in Python

Initializing SparkSession

Creating DataFrames

Fromm RDDs

Filter

Duplicate Values

Queries

Add, Update & Remove Columns

Missing & Replacing Values

GroupBy

Sort

Repartitioning

Running Queries Programmatically

Inspect Data

Output

Stopping SparkSession

How to Create a Responsive Dropdown Menu Bar with Search Field using HTML & CSS

Vaadin Grid renderers: customize cells and show a details row (Fusion)

Easy Activity Tracking for Models, Similar to Github's Public Activity

PublicActivity

!! WARNING: README for unreleased version below. !!

About

Tutorials

Screencast

Tutorial

Online demo

Setup

Gem installation

Database setup

Model configuration

Custom activities

Displaying activities

Layouts

Locals

Activity views

i18n

Testing

Documentation

Common examples

Set the Activity's owner to current_user by default

Disable tracking for a class or globally

Create custom activities

Instant options

Use custom fields on Activity

Set owner and recipient based on associations

Resolve parameters from a Symbol or Proc

Setup

Migration

Assigning custom fields

Help

Cells: View Components for Ruby and Rails

Cells

Overview

Full Documentation

Rendering Cells

Cell Class

Logicless Views

File Structure

Invocation Styles

Parameters

Testing

Properties

HTML Escaping

Installation

Namespaces

Rails Helper API

View Paths

Asset Packaging

Render API

Layouts

Nested Cells

View Inheritance

Collections

Builder

Caching

The Book

This is not Cells 3.x!

Set `owner` and `recipient` based on associations