Paloma

This README is for Paloma 4 only.

For version 3 README please go here.

For version 2 README please go here.

Paloma 4, why so sudden?

The last major version (v3) of Paloma introduced a major paradigm shift, and it took me a while to realize that some of the major changes introduced are not really that good and needed to be removed.

What's new?

(compared to version 2) It is now simpler and more flexible. The old callback thingy paradigm is replaced by a Controller layer for better abstraction. Generators are also removed, so programmers need not to follow specific directory structure, unlike in the old versions.

Previously, there are generators that create Paloma files, and these files are written in vanilla javascript. Because of that there are some users who are requesting for coffeescript setup. Now since there are no generated files programmers can write their code either by using vanilla javascript or coffeescript. Yay!

Controller

The new paradigm is patterned after Rails Controller, so it is easier to grasp than the old callback paradigm. Basically, you have a Paloma Controller counterpart for every Rails Controller.

How about Model and View?

It is tempting to convert Paloma 3 to a full-blown MVC or MVP (or whatever) framework. But I've decided to keep it simple and just provide a Controller component as way to execute a specific javascript code per Rails Controller action and give developers freedom on how to handle each action. So you can still have your own Model and View components and just use them in your Paloma Controllers, since a controller is just a middle-man.

Advantages

• Choose what specific javascript code to run per page.
• Easily make ruby variables available on your javascript files.

Quick Example

Paloma controller.

var UsersController = Paloma.controller('Users');

// Executes when Rails User#new is executed.
UsersController.prototype.new = function(){
   alert('Hello Sexy User!' );
};

The Rails controller app/controllers/users_controller.rb:

def UsersController < ApplicationController
    def new
      # a Paloma request will automatically be created.
      @user = User.new
    end
end

That's it! Simply Sexy!

Minimum Requirements

• jQuery 1.7 or higher
• Rails 3.1 or higher

Install

• Without bundler: sudo gem install paloma.
• With bundler, add this to your Gemfile: gem 'paloma'
• Require paloma in your application.js: //= require paloma

Controllers

Controllers are just classes that handle requests made by Rails Controllers. Each Rails Controller's action will be mapped to a specific Paloma Controller's action.

Creating a Controller

A Controller constructor is created or accessed (if it already exists), using Paloma.controller() method.

var ArticlesController = Paloma.controller('Articles');

It will return the constructor function of your controller.

Note: Using Paloma.controller method, you can access the same controller constructor across different files.

Handling Actions

Every time a request to Paloma is made (A Rails Controller action is executed), an instance of a Paloma controller is created and the method responsible for the request will be invoked.

var ArticlesController = Paloma.controller('Articles');

ArticlesController.prototype.new = function(){
  // Handle new articles
};

ArticlesController.prototype.edit = function(){
  // Handle edit articles
};

Advanced Usage

You can manipulate what controller/action should Paloma execute by calling js method before rendering.

1. Changing controller

   class UsersController < ApplicationController
      def new
         @user = User.new
         js 'Accounts' # will use Accounts controller instead of Users controller
      end
   end

2. Changing action

   You can use the symbol syntax:

   def new
      @user = User.new
      js :register # will execute register method instead of new
   end

   Or the string syntax:

   def new
      @user = User.new
      js '#register'
   end

3. Changing controller and action.

   def new
     @user = User.new
     js 'Accounts#register' # will execute Accounts#register instead of Users#new
   end

4. Changing controller with namespace.

   Paloma supports namespaces using '/' as delimiter.

   def new
      @user = User.new
      js `Admin/Accounts` # will use Admin/Accounts controller instead of Users controller
   end

   def new
      @user = User.new
      js 'Admin/Accounts#register' # will execute Admin/Accounts#register instead of Users#new
   end

Passing Parameters

You can access the parameters on your Paloma Controller using this.params object.

1. Parameters only.

   users_controller.rb

   def destroy
       user = User.find params[:id]
       user.destroy
       
       js :id => user.id
   end

   Paloma controller.

   var UsersController = Paloma.controller('Users');
   
   UsersController.prototype.destroy = function(){
     alert('User ' + this.params['id'] + ' is deleted.');
   };

2. Path with parameters.

   def destroy
      user = User.find params[:id]
      user.destroy
      
      js 'Accounts#delete', :id => user.id
   end

Preventing Paloma Execution

If you want to Paloma not to execute in a specific Rails Controller action you need to pass false as the Paloma parameter.

def edit
  @user = User.find params[:id]
  js false
end

Controller-wide setup

You can call js outside Rails controller actions for global or controller-wide settings.

Example:

class UsersController < ApplicationController
   js 'Accounts' # use Accounts controller instead of Users for all actions.


   def new
      @user = User.new
   end
   
   def show
      @user = User.find params[:id]
   end
end

Like before_filter you can also pass only and except options.

class UsersController < ApplicationController

   js 'Admin/Accounts', :except => :destroy # Use Admin/Accounts except for destroy method

end

IMPORTANT NOTE: If you are going to pass parameters for Controller-wide settings, put them inside a :params hash.

class UsersController < ApplicationController
  js 'Accounts', :params => {:x => 1, :y => 2, :z => 3}, :only => :show
end

Overriding Controller-wide setup

If you want to override the controller-wide setup, just call js again inside a controller action. From there you can override the controller/action or pass additional parameters.

class UsersController < ApplicationController

   js 'Accounts', :params => {:x => 1}
   
   
   def new
      @user = User.new
      js :register, :y => 2 # will execute Accounts#register with params {:x => 1, :y => 2}
   end
end

Turbolinks Support

As of version 4.1.0, Paloma is compatible with Turbolinks without additional setup.

Execute Paloma when user hits Back or Forward button.

Paloma executes page-specific javascript by adding a <script> tag to the response body. Turbolinks, by default, executes any inline javascript in the response body when you visit a page, so the <script> tag appended by Paloma will automatically be executed. However, when Turbolinks restores a page from cache (this happens when a user hits Back or Forward button in his browser) any inline javascript will not be executed anymore. This is the intentional behavior of Turbolinks, and it is not a bug. If you want to execute Paloma again when Turbolinks restores a page, do something like this:

$(document).on('page:restore', function(){
  // Manually evaluates the appended script tag.
  Paloma.executeHook();
});

Turbolinks without jquery.turbolinks gem

You need to manually run Paloma every page load if you are not using jquery.turbolinks gem.

In your application.js

$(document).on('page:load', function(){
   Paloma.executeHook();
   Paloma.engine.start();
});

Gotchas

• Paloma will execute on all render calls, except for calls with the following formats: js, json, xml, and file.

  Example:

  render :json => {:x => 1}  # Paloma will not execute`
  render :partial => '/path/to/partial'  # Paloma will execute

• It will cause conflicts if you have a controller and a module that has the same name.

  Example:

  var AdminController = Paloma.controller('Admin');
  
  // This will override the AdminController and replace it
  // with a module named 'Admin'.
  var UsersController = Paloma.controller('Admin/Users');

Where to put code?

Again, Paloma is now flexible and doesn't force developers to follow specific directory structure. You have the freedom to create controllers anywhere in your application.

Personally, I prefer having a javascript file for each controller.