paloma/README.md

# Paloma

**This README is for Paloma 4 only.**

**For version 3 README please go [here](https://github.com/kbparagua/paloma/blob/3.0/README.md).**

**For version 2 README please go [here](https://github.com/kbparagua/paloma/blob/2.0/README.md).**


## 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.

```javascript
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`:

```ruby
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.

```javascript
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 a method responsible for the request will be invoked.
 
```javascript
var ArticlesController = Paloma.controller('Articles');

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

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

## Passing Parameters

You can also pass parameters to a Paloma Controller by calling `js` **before** render in your Rails controller. You can access the parameters on your Paloma Controller using `this.params` object.

**Example:**

`users_controller.rb`
```ruby
def destroy
    user = User.find params[:id]
    user.destroy
    
    js :id => user.id
end
```

Paloma controller.

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

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

## 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.

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


## Gotchas

* Paloma  will not execute if the response is `js`, `json`, `xml` or any other format except `html`.

For example: `render "something.js.erb"`


## 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 and routes anywhere in your application.

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