Module: ActiveModel::Conversion

Defined in:
activemodel/lib/active_model/conversion.rb

Overview

Active Model Conversions

Handles default conversions: to_model, to_key and to_param.

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

Instance Method Summary (collapse)

Instance Method Details

- (Object) 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.



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

def to_key
  persisted? ? [id] : nil
end

- (Object) 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.



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# File 'activemodel/lib/active_model/conversion.rb', line 30

def to_model
  self
end

- (Object) to_param

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



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# File 'activemodel/lib/active_model/conversion.rb', line 45

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