How to create a Rails Plugin?

What is a Rails plugin?
A Rails plugin is either an extension or a modification of the core framework. It provides a way for rails developer to share bleeding-edge ideas without hurting the stable code base. We need to decide if our plugin will be potentially shared across different Rails applications.

A plugin creates models, view helpers, controllers, rake tasks, images, style sheets, javascripts, test assertions and unit and functional tests like rails application.

How to create a plugin?

desktop:~$  ruby /script/generate plugin HelloWorld  (In rails < 3 version)

desktop:~$ rails generate plugin HelloWorld  (In rails >= 3 version)

create  vendor/plugins/hello_world/lib

create  vendor/plugins/hello_world/tasks

create  vendor/plugins/hello_world/test

create  vendor/plugins/hello_world/README

create  vendor/plugins/hello_world/Rakefile

create  vendor/plugins/hello_world/init.rb

create  vendor/plugins/hello_world/install.rb

create  vendor/plugins/hello_world/lib/hello_world.rb

create  vendor/plugins/hello_world/tasks/hello_world_tasks.rake

create  vendor/plugins/hello_world/test/hello_world_test.rb

Plugin structure as,

 HelloWorld

|-- init.rb

|-- install.rb

|-- Rakefile

|-- README

|-- lib/

|   |-- hello_world.rb

|-- tasks/

|   |-- hello_world_tasks.rake

|-- test

|   |-- hello_world_test.rb

Plugin HelloWorld structure:

Here,

    ->  init.rb: Runs every time the rails app gets started. It is useful for mixing-in a helper module so that all of our ‘views’ can use it.

    -> install.rb: Runs one time only when the plugin is first installed.

    -> Rakefile: Generates documentation and runs tests for the created plugin.

    -> lib/: Contains actual ruby code. New models and other libraries in this folder will be automatically available to rails app. Helpers can be included specially, using the init.rb file.

   -> tasks/: Drop a .rake file here as you would in lib/tasks.

    -> test/: Write tests to verify the task of our plugin.

We need hello_world/init.rb and main class in hello_world/lib/hello_world.rb to create a simple rails plugin.

We just add the required 'hello_world' in init.rb file, then create the main class hello_world.rb under hello_world/lib/ folder like the structure,

class HelloWorld

  def display

    "Hello World!"

  end  

end

That's it. We can add this plugin method in our rails controller to show the 'Hello World'.

class SamplesController < ApplicationController

   def index

    @show = HelloWorld.new  # @show is an object to the HelloWorld class

  end

end

In app/views/samples/index.html.erb

<p><%= @show.display %></p>

It shows Hello World!

Note: Restart the server if you are going to do some modifications in the plugin.

Ruby on rails consulting for Mac, Windows or Linux can make application development faster and simpler using rails plugins.