Question

我有以下相互依赖的模型：

from mongoengine import *

class DocumentA(Document):
    docB = ReferenceField('DocumentB', reverse_delete_rule=CASCADE)

class DocumentB(Document):
    docA = ReferenceField('DocumentA', reverse_delete_rule=CASCADE)

我收到以下错误：

mongoengine.errors.NotRegistered: `DocumentB` has not been registered in the document registry.
            Importing the document class automatically registers it, has it
            been imported?

如果我删除第一个reverse_delete_rule：

，则此错误消失

from mongoengine import *

class DocumentA(Document):
    docB = ReferenceField('DocumentB')

class DocumentB(Document):
    docA = ReferenceField('DocumentA', reverse_delete_rule=CASCADE)

工作正常。

有没有办法保留reverse_delete_rule？

Answer 1

来自MongoEngine ReferenceField documentation：

注册删除规则的替代语法（在使用时有用）实施双向删除规则）
class Bar(Document):
    content = StringField()
    foo = ReferenceField('Foo')

Foo.register_delete_rule(Bar, 'foo', NULLIFY)

所以你的代码变成了：

from mongoengine import *

class DocumentA(Document):
    docB = ReferenceField('DocumentB')

class DocumentB(Document):
    docA = ReferenceField('DocumentA', reverse_delete_rule=CASCADE)

DocumentB.register_delete_rule(DocumentA, 'docB', CASCADE)

Mongoengine中与reverse_delete_rule的循环依赖

1 个答案: