json_type.py 文件源码

def load_dialect_impl(self, dialect: dialects) -> DialectType:
        """
        SQLAlchemy wraps all database-specific features into
        dialects, which are then responsible for generating the SQL code
        for a specific DB type when loading in data. ``load_dialect_impl``
        is called when CRUD (create, update, delete operations) needs to be
        done on the database. This method is responsible for telling
        SQLAlchemy how to configure the dialect to write this type

        :param dialect: The loaded dialect
        :return: The type descriptor for this type.
        """
        if dialect.name == 'postgresql':
            return dialect.type_descriptor(postgresql.JSON())
        elif dialect.name == 'mysql':
            if 'JSON' in dialect.ischema_names:
                return dialect.type_descriptor(mysql.JSON())
            else:
                return dialect.type_descriptor(
                    VARCHAR(self._MAX_VARCHAR_LIMIT)
                )
        else:
            return dialect.type_descriptor(VARCHAR(self._MAX_VARCHAR_LIMIT))