Adding to_key to ActiveResource objects using ActiveModel::Conversion [#4685 state:resolved]

Signed-off-by: José Valim <jose.valim@gmail.com>

activeresource/lib/active_resource/base.rb

@@ -1044,11 +1044,6 @@ module ActiveResource
       attributes[self.class.primary_key] = id
     end
 
-    # Allows Active Resource objects to be used as parameters in Action Pack URL generation.
-    def to_param
-      id && id.to_s
-    end
-
     # Test for equality.  Resource are equal if and only if +other+ is the same object or
     # is an instance of the same class, is not <tt>new?</tt>, and has the same +id+.
     #
@@ -1411,6 +1406,7 @@ module ActiveResource
   class Base
     extend ActiveModel::Naming
     include CustomMethods, Observing, Validations
+    include ActiveModel::Conversion
     include ActiveModel::Serializers::JSON
     include ActiveModel::Serializers::Xml
   end

activeresource/test/cases/base_test.rb

@@ -1081,6 +1081,13 @@ class BaseTest < Test::Unit::TestCase
     assert_equal '1', matz.to_param
   end
 
+  def test_to_key_quacks_like_active_record
+    new_person = Person.new
+    assert_nil new_person.to_key
+    matz = Person.find(1)
+    assert_equal [1], matz.to_key
+  end
+
   def test_parse_deep_nested_resources
     luis = Customer.find(1)
     assert_kind_of Customer, luis