如何使用SQLAlchemy TypeDecorators编译原始SQL

uuid.UUID :

import uuid
import sqlalchemy

foreign_uuid = '822965bb-c67e-47ee-ad12-a3b060ef79ae'
qry = Query(MyModel).filter(MyOtherModel.uuid == uuid.UUID(foreign_uuid))

现在我想从SQLAlchemy获取原始postgresql:

qry.statement.compile(dialect=postgresql.dialect(), compile_kwargs={"literal_binds": True}))

这会产生以下错误: NotImplementedError: Don't know how to literal-quote value UUID('822965bb-c67e-47ee-ad12-a3b060ef79ae')

这似乎是因为SqlAlchemy只知道如何处理基本类型。 The documentation suggests TypeDecorator 甚至还为guid提供了一个:

from sqlalchemy.dialects.postgresql import UUID
import uuid

class GUID(TypeDecorator):
    """Platform-independent GUID type.

    Uses PostgreSQL's UUID type, otherwise uses
    CHAR(32), storing as stringified hex values.

    """
    impl = CHAR

    def load_dialect_impl(self, dialect):
        if dialect.name == 'postgresql':
            return dialect.type_descriptor(UUID())
        else:
            return dialect.type_descriptor(CHAR(32))

    def process_bind_param(self, value, dialect):
        if value is None:
            return value
        elif dialect.name == 'postgresql':
            return str(value)
        else:
            if not isinstance(value, uuid.UUID):
                return "%.32x" % uuid.UUID(value).int
            else:
                # hexstring
                return "%.32x" % value.int

    def process_result_value(self, value, dialect):
        if value is None:
            return value
        else:
            if not isinstance(value, uuid.UUID):
                value = uuid.UUID(value)
            return value

但是它没有说怎么做 使用 打字机 . 我需要在我的模型中引用它吗?我能把它提供给 .statement.compile 打电话?