# ScopedFrom

Provides a simple mapping between scopes and controller parameters for
[Ruby On Rails 3](http://rubyonrails.org/).

## Installation

Just add this into your `Gemfile`:

    gem 'scoped_from'

Then, just run `bundle install`.

## Example

First, a model with some scopes:

    class Post < ActiveRecord::Base
    
      scope :commented, where('comments_count > 0')

      scope :created_between, lambda { |after, before|
        where('created_at >= ? AND created_at <= ?', after, before)
      }
      
      scope :search, lambda { |pattern|
        where('body LIKE ?', "%#{pattern}%")
      }
      
      scope :with_category, lambda { |category_id|
        where(:category_id, category_id)
      }
    
    end
    
After, a controller:
    
    class PostsController < ActionController::Base
    
      def index
        @posts = Post.scoped_from(params)
      end
    
    end
    
Then, it just filter your model from params:
    
    /posts?commented=1
    /posts?search=rails
    /posts?search=rails&commented=1&with_category=42

## Accepted scopes

All scopes can be mapped with `scoped_from` method **except** scopes taking a
`lambda` (or a `Proc`) with an arity greater than 1 (for example:
`created_between` in the above code).

Scopes with no argument are invoked if parameter value is evaluated as `true`.
It includes `"true"`, `"yes"`, `"y"`, `"on"`, and `"1"` strings.

Columns are also automatically scoped.

## Scopes restriction

You can restrict mapping to some scopes with `:only` option:

    @posts = Post.scoped_from(params, :only => ['commented', 'search'])

You can also exclude some scopes from mapping with `:except` option:

    @posts = Post.scoped_from(params, :except => 'commented')

## Mapping order

If you need to map an SQL order, just pass `order` parameter:

    @posts = Post.scoped_from(:order => 'created_at')

Order direction can be specified using a dot, space or `:` as delimiter:
    
    @posts = Post.scoped_from(:order => 'created_at.desc')

Note that order is SQL safe with `scoped_from` method (columns names are
checked).

## Some cool stuff

If your provide an array as parameter value, scope is invoked with each item
of the array:

    @posts = Post.scoped_from(:search => ['bar', 'foo'])
    
is equivalent to
    
    @posts = Post.search('bar').search('foo')

You may also not want to filter on columns, just specify `:exclude_columns`
option:

    @posts = Post.scoped_from(params, :exclude_columns => true)

A query string can also be given to `scoped_from` method:

    @posts = Post.scoped_from('with_category=24&search[]=foo&search[]=bar')

Returned scope from `scoped_from` method gives access to an internal query
object:

    @posts = Post.scoped_from(params)
    @query = @posts.query

This query provides you some convenience methods like `params`, `order_column`
and `order_direction`. This object can also be used to save user's search into
a database or other storage system.

But, you may also have to subclass this query class. You have to create a
subclass of `ScopedFrom::Query` named `#{RecordClassName}Query`. Here is an
example:

    class PostQuery < ScopedFrom::Query
    
      def category
        Category.find_by_id(params[:with_category]) if params[:with_category]
      end
    
    end

This class has to be in load path.
    
Then into a view:

    <% if @query.category %>
      <p>All posts of category <%= @query.category.name %></p>
    <% else %>
      <p>All posts</p>
    <% end %>

## Executing test suite

This project is fully tested with [Rspec 2](http://github.com/rspec/rspec).
Just run `bundle exec rake` (after a `bundle install`).