python - 是否可以在 ReferenceFields 上使用 unique_with ？

Question

我无法在 MongoEngine 中使用 unique_with 处理 ReferenceFields。我的模型如下所示:

class WorkoutSchedule(database.Document):
    """ Defines a workout schedule """
    user = database.ReferenceField(User)
    title = database.StringField(
        required=True,
        min_length=3,
        max_length=30,
        unique_with=user)

如果 user 和 title 相同，我希望文档是唯一的。但是，这会引发异常:

TypeError: Error when calling the metaclass bases
    'ReferenceField' object is not iterable

是否可以使用 unique_with 和 ReferenceFields 还是我必须手动解决这个问题？

Answer 1

查看文档 https://mongoengine-odm.readthedocs.org/en/latest/guide/defining-documents.html?highlight=unique_with#field-arguments :

unique_with (Default: None)
    A field name (or list of field names) that when taken together 
    with this field, will not have two documents in the collection
    with the same value.

因此 unique_with 必须是字段名称的 basestring 或 list 的 basestring:

class WorkoutSchedule(database.Document):
    """ Defines a workout schedule """
    user = database.ReferenceField(User)
    title = database.StringField(
        required=True,
        min_length=3,
        max_length=30,
        unique_with=['user'])