Module: ActiveModel::Conversion

Extended by:
ActiveSupport::Concern
Included in:
ActiveRecord::Base
Defined in:
activemodel/lib/active_model/conversion.rb

Overview

Active Model Conversion

Handles default conversions: to_model, to_key, to_param, and to_partial_path.

Let's take for example this non-persisted object.

class ContactMessage
  include ActiveModel::Conversion

  # ContactMessage are never persisted in the DB
  def persisted?
    false
  end
end

cm = ContactMessage.new
cm.to_model == cm  # => true
cm.to_key          # => nil
cm.to_param        # => nil
cm.to_partial_path # => "contact_messages/contact_message"

Defined Under Namespace

Modules: ClassMethods

Instance Method Summary collapse

Methods included from ActiveSupport::Concern

append_features, extended, included

Instance Method Details

#to_keyObject

Returns an Enumerable of all key attributes if any is set, regardless if the object is persisted or not. If there no key attributes, returns nil.

class Person < ActiveRecord::Base
end

person = Person.create
person.to_key # => [1]

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# File 'activemodel/lib/active_model/conversion.rb', line 51

def to_key
  key = respond_to?(:id) && id
  key ? [key] : nil
end

#to_modelObject

If your object is already designed to implement all of the Active Model you can use the default :to_model implementation, which simply returns self.

class Person
  include ActiveModel::Conversion
end

person = Person.new
person.to_model == person # => true

If your model does not act like an Active Model object, then you should define :to_model yourself returning a proxy object that wraps your object with Active Model compliant methods.


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# File 'activemodel/lib/active_model/conversion.rb', line 39

def to_model
  self
end

#to_paramObject

Returns a string representing the object's key suitable for use in URLs, or nil if persisted? is false.

class Person < ActiveRecord::Base
end

person = Person.create
person.to_param # => "1"

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# File 'activemodel/lib/active_model/conversion.rb', line 64

def to_param
  persisted? ? to_key.join('-') : nil
end

#to_partial_pathObject

Returns a string identifying the path associated with the object. ActionPack uses this to find a suitable partial to represent the object.

class Person
  include ActiveModel::Conversion
end

person = Person.new
person.to_partial_path # => "people/person"

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# File 'activemodel/lib/active_model/conversion.rb', line 77

def to_partial_path
  self.class._to_partial_path
end