Keep column defaults in type cast form

The contract of `_field_changed?` assumes that the old value is always
type cast. That is not the case for the value in `Column#default` as
things are today. It appears there are other public methods that
assume that `Column#default` is type cast, as well. The reason for this
change originally was because the value gets put into `@raw_attributes`
in initialize. This reverts to the old behavior on `Column`, and updates
`initialize` to make sure that the values are in the right format.

1 files changed, 28 insertions, 0 deletions

diff --git a/activerecord/test/cases/dirty_test.rb b/activerecord/test/cases/dirty_test.rb
index df4183c065..987c55ebc2 100644
--- a/activerecord/test/cases/dirty_test.rb
+++ b/activerecord/test/cases/dirty_test.rb
@@ -616,6 +616,34 @@ class DirtyTest < ActiveRecord::TestCase
     end
   end
 
+  test "defaults with type that implements `type_cast_for_write`" do
+    type = Class.new(ActiveRecord::Type::Value) do
+      def type_cast(value)
+        value.to_i
+      end
+
+      def type_cast_for_write(value)
+        value.to_s
+      end
+
+      alias type_cast_for_database type_cast_for_write
+    end
+
+    model_class = Class.new(ActiveRecord::Base) do
+      self.table_name = 'numeric_data'
+      property :foo, type.new, default: 1
+    end
+
+    model = model_class.new
+    assert_not model.foo_changed?
+
+    model = model_class.new(foo: 1)
+    assert_not model.foo_changed?
+
+    model = model_class.new(foo: '1')
+    assert_not model.foo_changed?
+  end
+
   private
     def with_partial_writes(klass, on = true)
       old = klass.partial_writes?