1 files changed, 17 insertions, 8 deletions
diff --git a/activemodel/lib/active_model/type/float.rb b/activemodel/lib/active_model/type/float.rb
index 0f925bc7e1..4d0d2771a0 100644
--- a/activemodel/lib/active_model/type/float.rb
+++ b/activemodel/lib/active_model/type/float.rb
@@ -7,19 +7,28 @@ module ActiveModel
         :float
       end
 
+      def type_cast_for_schema(value)
+        return "::Float::NAN" if value.try(:nan?)
+        case value
+        when ::Float::INFINITY then "::Float::INFINITY"
+        when -::Float::INFINITY then "-::Float::INFINITY"
+        else super
+        end
+      end
+
       alias serialize cast
 
       private
 
-      def cast_value(value)
-        case value
-        when ::Float then value
-        when "Infinity" then ::Float::INFINITY
-        when "-Infinity" then -::Float::INFINITY
-        when "NaN" then ::Float::NAN
-        else value.to_f
+        def cast_value(value)
+          case value
+          when ::Float then value
+          when "Infinity" then ::Float::INFINITY
+          when "-Infinity" then -::Float::INFINITY
+          when "NaN" then ::Float::NAN
+          else value.to_f
+          end
         end
-      end
     end
   end
 end