Working With Rails

Meantime Filter

= meantime_filter for Rails controllers

A plugin for Ruby On Rails extending ActionController features. It works with Rails v1.1.4, it has not been tested with other versions.

Description This plugin introduces a new filter type to ActionController::Base: meantime filters. They are called at the time of the action call just after before filters. They allow to do things around the action by yielding when the action has to be performed. This enables the action to be executed within the block of any method. Getting and installing it 1. In order to get and install it, download the plugin archive file from: meantime_filter-0.1.0.tar.gz[http://roman2k.free.fr/rails/meantime_filter/0.1.0/plugin/meantime_filter-0.1.0.tar.gz]

2. Gunzip and untar it in the plugin/ subdirectory of your Rails application.

Example of reason to use it I have written this plugin because I needed to scope an ActiveRecord model during the actions I specify with its with_scope class method that takes a block and it was not possible to reproduce its behaviour with before and after filters since there is no method to scope without a block and no method to remove the last scope.

With meantime filters, it's possible to do such things in a simple and clean manner.

I think it is a better way to do things both before and after actions than using an around filter because yield is made for that type of task.

Usage This plugins adds three public class methods to ActionController::Base: * meantime_filter (ActionController::Filters::MeantimeFilter::ClassMethods.meantime_filter) * append_meantime_filter (ActionController::Filters::MeantimeFilter::ClassMethods.append_meantime_filter) * prepend_meantime_filter (ActionController::Filters::MeantimeFilter::ClassMethods.prepend_meantime_filter) They all accept one or more filters as parameter(s) and the same conditions hash as before and after filters registering methods as last parameter. A filter:

• Can be either: * A Symbol that is the name of one of the controller’s instance methods, * A Method that takes the controller as only parameter, * Any object that responds to :filter and whose filter method takes the controller as only parameter.
• Cannot be a Proc because Procs cannot yield unfortunately.

And of course, it must either:

• Contain a yield statement,
• Call the block it received, or
• Pass the received block to another method.

=== Nested filtering You can even nest several meantime filters by registering several ones for the same action(s). They are executed in the same order as they have been register through meantime_filter. The first filter yields to the second that yields to the third and so on. The last one yields the action.

Usage example

class PostsController < ApplicationController
  before_filter :authenticate
  meantime_filter :scope_posts_to_user
end

1. Displays the posts of the logged in user. def show @posts = Post.find(:all) end

def create
  # ...
  @post = Post.create(params[:post]) # Automatically associated to @user
  # ...
end

private

1. Sets @user to the logged in user or redirects to :index. def authenticate # ... end

def scope_posts_to_user(&block)
  Post.with_scope({
    :find => { :conditions => [ 'user_id = ?', @user.id ]},
    :create => { :user => @user }
  }, &block)
end

1. Or: def scope_posts_to_user Post.with_scope({ :find => { :conditions => [ ‘user_id = ?’, @user.id ]}, :create => { :user => @user } }) { yield } end

Tests of the plugin This plugin is packaged with unit tests. They are ready-to-run. Go in the tests/ subdirectory and run rake. Author {Roman LE NEGRATE}[mailto:roman2k@free.fr] Licence Copyright© 2006 Roman LE NEGRATE

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

Happy coding with Ruby and Rails :-).

NOTE: This description has been extracted from the Plugin README and so the formatting may need updating to make browser friendly