Active Model Conversions

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 == self # => true
cm.to_key           # => nil
cm.to_param         # => nil
cm.to_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.

Note the default implementation uses persisted? just because all objects in Ruby 1.8.x responds to :id.

Source: show | on GitHub 

# File activemodel/lib/active_model/conversion.rb, line 45
def to_key
  persisted? ? [id] : 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.

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 36
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.

Source: show | on GitHub 

# File activemodel/lib/active_model/conversion.rb, line 51
def to_param
  persisted? ? to_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.

Source: show | on GitHub 

# File activemodel/lib/active_model/conversion.rb, line 57
def to_partial_path
  self.class._to_partial_path
end