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"
Methods
T
Instance Public methods
to_key()

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]

Source: show | on GitHub 

# File activemodel/lib/active_model/conversion.rb, line 51
def to_key
  key = respond_to?(:id) && id
  key ? [key] : nil
end
to_model()

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.

Source: show | on GitHub 

# File activemodel/lib/active_model/conversion.rb, line 39
def to_model
  self
end
to_param()

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"

Source: show | on GitHub 

# File activemodel/lib/active_model/conversion.rb, line 64
def to_param
  (persisted? && key = to_key) ? key.join('-') : nil
end
to_partial_path()

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"

Source: show | on GitHub 

# File activemodel/lib/active_model/conversion.rb, line 77
def to_partial_path
  self.class._to_partial_path
end