Description

Injection is a simple dependency injection plugin for Rails 3. It allows you to inject objects into your controllers and observers which have been described in a yaml file (config/objects.yml).

(for the Rails 2 plugin install from the rails_2_plugin tag of this repository)

Features

  • Declarative dependency injection that automatically instantiates ivars via the objects.yml file

Synopsis

To specify objects to be injected from the DIY context into your controller or observer
use the inject class method:

  inject :one_component, :another

Example

This example defines a context with two objects, _foo_ and _bar_, which 
are injected into every instance of the WidgetController or WidgetObserver.  The objects 
are available as instance variables within the controller and observer.

config/objects.yml:
  ---
  foo:
  bar:

lib/foo.rb:
  class Foo
    ...
  end

lib/bar.rb:
  class Bar
    ...
  end

app/controllers/widget_controller.rb:
  class WidgetController < ApplicationController
    inject :foo, :bar

    def index
      render :text => "{@foo.inspect} {@bar.inspect}"
    end
  end

app/models/widget_observer.rb:
  class WidgetObserver < ActiveRecord::Observer
    inject :foo, :bar

    before :save do |widget|
     @foo.bar(widget)
     @bar.foo(widget)
    end
  end

Declarative Observations

Observations on an Active Record object can be specified in a declarative way using
the before and after class methods. The methods are invoked with a
symbol which specifies what kind of event the observer is interested in, and a block 
that defines what actions it will perform.

  class WidgetObserver < ActiveRecord::Observer
    before :update do |record|
      ...
    end

    after :create do |record|
      ...
    end

    after :validation do |record|
      ...
    end

    before :validation do |record|
      ...
    end
  end

Requirements

Install

  • gem install injection

License

(The MIT License)

Copyright © 2007-2011 Atomic Object

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.