def _get_default_column_value(column_type):
 type_schema = {'datetime': None, 'big_integer': 0, 'integer': 0, 'string': ''}
 if isinstance(column_type, sa_sql.type_api.Variant):
  return _get_default_column_value(column_type.impl)
 return type_schema[column_type.__visit_name__]

def _get_default_column_value ( column_type ) : type_schema = { 'datetime' : None , 'big_integer' : 0 , 'integer' : 0 , 'string' : '' } if isinstance ( column_type , sa_sql . type_api . Variant ) : return _get_default_column_value ( column_type . impl ) return type_schema [ column_type . __visit_name__ ]
return the default value of the columns from db table in postgredb case .