Work around the fact the JSON gem was overwriting to_json implementation for all Ruby core classes.

This is required because the JSON gem is incompatible with Rails behavior and was not allowing ActiveModel::Errors to be serialized.
So we need to ensure Rails implementation is the one triggered. [#4890 state:resolved]

1 files changed, 14 insertions, 5 deletions

diff --git a/activesupport/lib/active_support/json/encoding.rb b/activesupport/lib/active_support/json/encoding.rb
index 02c233595d..dd94315111 100644
--- a/activesupport/lib/active_support/json/encoding.rb
+++ b/activesupport/lib/active_support/json/encoding.rb
@@ -128,12 +128,21 @@ module ActiveSupport
   end
 end
 
-class Object
-  # Dumps object in JSON (JavaScript Object Notation). See www.json.org for more info.
-  def to_json(options = nil)
-    ActiveSupport::JSON.encode(self, options)
-  end
+# The JSON gem adds a few modules to Ruby core classes containing :to_json definition, overwriting
+# their default behavior. That said, we need to define the basic to_json method in all of them,
+# otherwise they will always use to_json gem implementation, which is backwards incompatible in
+# several cases (for instance, the JSON implementation for Hash does not work) with inheritance
+# and consequently classes as ActiveSupport::OrderedHash cannot be serialized to json.
+[Object, Array, FalseClass, Float, Hash, Integer, NilClass, String, TrueClass].each do |klass|
+  klass.class_eval <<-RUBY, __FILE__, __LINE__
+    # Dumps object in JSON (JavaScript Object Notation). See www.json.org for more info.
+    def to_json(options = nil)
+      ActiveSupport::JSON.encode(self, options)
+    end
+  RUBY
+end
 
+class Object
   def as_json(options = nil) #:nodoc:
     if respond_to?(:to_hash)
       to_hash