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"
Returns an Enumerable of all key attributes if any is set, regardless if the object is persisted or not. Returns nil
if there are no key attributes.
class Person < ActiveRecord::Base end person = Person.create person.to_key # => [1]
# File activemodel/lib/active_model/conversion.rb, line 51 def to_key key = respond_to?(:id) && id key ? [key] : nil end
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.
# File activemodel/lib/active_model/conversion.rb, line 39 def to_model self end
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"
# File activemodel/lib/active_model/conversion.rb, line 64 def to_param (persisted? && key = to_key) ? key.join('-') : nil end
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"
# File activemodel/lib/active_model/conversion.rb, line 77 def to_partial_path self.class._to_partial_path end
© 2004–2016 David Heinemeier Hansson
Licensed under the MIT License.