Don't type cast the default on the column

If we want to have type decorators mess with the attribute, but not the
column, we need to stop type casting on the column. Where possible, we
changed the tests to test the value of `column_defaults`, which is
public API. `Column#default` is not.

1 files changed, 6 insertions, 7 deletions

diff --git a/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb b/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
index a9b97d5919..3ef8878ad1 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
@@ -62,15 +62,14 @@ module ActiveRecord
           @extra     = extra
           super(name, default, cast_type, sql_type, null)
           assert_valid_default(default)
+          extract_default
         end
 
-        def default
-          @default ||= if blob_or_text_column?
-            null || strict ? nil : ''
-          elsif missing_default_forged_as_empty_string?(@original_default)
-            nil
-          else
-            super
+        def extract_default
+          if blob_or_text_column?
+            @default = null || strict ? nil : ''
+          elsif missing_default_forged_as_empty_string?(@default)
+            @default = nil
           end
         end