enable AS::JSON.encode to encode AR::Relation by providing `as_json` method

[#5073 state:resolved]

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

2 files changed, 10 insertions, 1 deletions

diff --git a/activerecord/lib/active_record/relation.rb b/activerecord/lib/active_record/relation.rb
index d9fc1b4940..7499100f55 100644
--- a/activerecord/lib/active_record/relation.rb
+++ b/activerecord/lib/active_record/relation.rb
@@ -10,7 +10,7 @@ module ActiveRecord
 
     include FinderMethods, Calculations, SpawnMethods, QueryMethods, Batches
 
-    delegate :to_xml, :to_json, :to_yaml, :length, :collect, :map, :each, :all?, :include?, :to => :to_a
+    delegate :to_xml, :to_yaml, :length, :collect, :map, :each, :all?, :include?, :to => :to_a
     delegate :insert, :to => :arel
 
     attr_reader :table, :klass
@@ -74,6 +74,8 @@ module ActiveRecord
       @records
     end
 
+    def as_json(options = nil) to_a end #:nodoc:
+
     # Returns size of the records.
     def size
       loaded? ? @records.length : count
diff --git a/activerecord/test/cases/json_serialization_test.rb b/activerecord/test/cases/json_serialization_test.rb
index c275557da8..2bc746c0b8 100644
--- a/activerecord/test/cases/json_serialization_test.rb
+++ b/activerecord/test/cases/json_serialization_test.rb
@@ -201,4 +201,11 @@ class DatabaseConnectedJsonEncodingTest < ActiveRecord::TestCase
     }
     assert_equal %({"1":{"author":{"name":"David"}}}), ActiveSupport::JSON.encode(authors_hash, :only => [1, :name])
   end
+
+  def test_should_be_able_to_encode_relation
+    authors_relation = Author.where(:id => [@david.id, @mary.id])
+    
+    json = ActiveSupport::JSON.encode authors_relation, :only => :name
+    assert_equal '[{"author":{"name":"David"}},{"author":{"name":"Mary"}}]', json
+  end
 end