= ActivePresenter

ActivePresenter is the presenter library you already know! (...if you know ActiveRecord)

By acting nearly identically to ActiveRecord models, ActivePresenter makes presenters highly approachable to anybody who is already familiar with ActiveRecord.

== Get It

As a gem:

  $ sudo gem install active_presenter

As a rails gem dependency:

  config.gem 'active_presenter'
  
Or get the source from github:
  
  $ git clone git://github.com/giraffesoft/active_presenter.git
  
(or fork it at http://github.com/giraffesoft/active_presenter)
    
== Usage

Creating a presenter is as simple as subclassing ActivePresenter::Base. Use the presents method to indicate which models the presenter should present.

  class SignupPresenter < ActivePresenter::Base
    presents User, Account
  end

=== Instantiation

Then, you can instantiate the presenter using either, or both of two forms. 

For example, if you had a SignupPresenter that presented User, and Account, you could specify arguments in the following two forms:
  
  1. SignupPresenter.new(:user_login => 'james', :user_password => 'swordfish', :user_password_confirmation => 'swordfish', :account_subdomain => 'giraffesoft')

    - This form is useful for initializing a new presenter from the params hash: i.e. SignupPresenter.new(params[:signup_presenter])
    
  2. SignupPresenter.new(:user => User.find(1), :account => Account.find(2))

    - This form is useful if you have instances that you'd like to edit using the presenter. You can subsequently call presenter.update_attributes(params[:signup_presenter]) just like with a regular AR instance.

Both forms can also be mixed together: SignupPresenter.new(:user => User.find(1), :user_login => 'james'). 

In this case, the login attribute will be updated on the user instance provided.
 
If you don't specify an instance, one will be created by calling Model.new

=== Validation
  
The #valid? method will return true or false based on the validity of the presented objects. 

This is calculated by calling #valid? on them.

You can retrieve the errors in two ways. 
  
  1. By calling #errors on the presenter, which returns an instance of ActiveRecord::Errors where all the attributes are in type_name_attribute_name form (i.e. You'd retrieve an error on User#login, by calling @presenter.errors.on(:user_login)).
  
  2. By calling @presenter.user_errors, or @presenter.user.errors to retrieve the errors from one presentable.
  
Both of these methods are compatible with error_messages_for. It just depends whether you'd like to show all the errors in one block, or whether you'd prefer to break them up.

=== Saving

You can save your presenter the same way you'd save an ActiveRecord object. Both #save, and #save! behave the same way they do on a normal AR model.

== Credits

ActivePresenter was created, and is maintained by {Daniel Haran}[http://danielharan.com] and {James Golick}[http://jamesgolick.com] on the train ride to {RubyFringe}[http://rubyfringe.com] from Montreal.

== License

ActivePresenter is available under the {MIT License}[http://en.wikipedia.org/wiki/MIT_License]