1 files changed, 34 insertions, 0 deletions
diff --git a/activemodel/lib/active_model/type/helpers/numeric.rb b/activemodel/lib/active_model/type/helpers/numeric.rb
new file mode 100644
index 0000000000..c883010506
--- /dev/null
+++ b/activemodel/lib/active_model/type/helpers/numeric.rb
@@ -0,0 +1,34 @@
+module ActiveModel
+  module Type
+    module Helpers
+      module Numeric # :nodoc:
+        def cast(value)
+          value = case value
+                  when true then 1
+                  when false then 0
+                  when ::String then value.presence
+                  else value
+                  end
+          super(value)
+        end
+
+        def changed?(old_value, _new_value, new_value_before_type_cast) # :nodoc:
+          super || number_to_non_number?(old_value, new_value_before_type_cast)
+        end
+
+        private
+
+        def number_to_non_number?(old_value, new_value_before_type_cast)
+          old_value != nil && non_numeric_string?(new_value_before_type_cast)
+        end
+
+        def non_numeric_string?(value)
+          # 'wibble'.to_i will give zero, we want to make sure
+          # that we aren't marking int zero to string zero as
+          # changed.
+          value.to_s !~ /\A-?\d+\.?\d*\z/
+        end
+      end
+    end
+  end
+end