First run failure of change_column while dropping constraint. Fixes #420.

Thanks @GrumpyRainbow @rkr090

Author: metaskills

CHANGELOG.md

@@ -4,6 +4,7 @@
 
 * Undefined method `database_prefix_remote_server?' Fixes #450. Thanks @jippeholwerda
 * Document two methods for avoiding N'' quoting on char/varchar columns.
+* First run failure of `change_column` while dropping constraint. Fixes #420. Thanks @GrumpyRainbow @rkr090
 
 #### Changed
 

lib/active_record/connection_adapters/sqlserver/schema_statements.rb

@@ -96,6 +96,7 @@ def change_column(table_name, column_name, type, options = {})
         end
 
         def change_column_default(table_name, column_name, default)
+          schema_cache.clear_table_cache!(table_name)
           remove_default_constraint(table_name, column_name)
           column_object = schema_cache.columns(table_name).find { |c| c.name.to_s == column_name.to_s }
           do_execute "ALTER TABLE #{quote_table_name(table_name)} ADD CONSTRAINT #{default_constraint_name(table_name, column_name)} DEFAULT #{quote_default_value(default, column_object)} FOR #{quote_column_name(column_name)}"