python - 访问 Mongo 文档的 id 字段引发 "TypeError: need one of hex, bytes, bytes_le, fields, or int"

Question

我想为文档添加一条记录，然后获取生成的id。但是，当我尝试访问 user_id 时，出现错误 TypeError: need one of hex, bytes, bytes_le, fields, or int。为什么会出现此错误？

class User(db.DynamicDocument):
    user_id = db.UUIDField(primary_key=True, required=True, default=uuid.UUID)
    ...

user = User().save()
user_id = user.user_id

File "views.py", line 15, in post
    user = User().save()
  File "/usr/local/lib/python2.7/dist-packages/mongoengine/base/document.py", line 96, in __init__
    setattr(self, key, value)
  File "/usr/local/lib/python2.7/dist-packages/mongoengine/base/document.py", line 188, in __setattr__
    super(BaseDocument, self).__setattr__(name, value)
  File "/usr/local/lib/python2.7/dist-packages/mongoengine/base/fields.py", line 123, in __set__
    value = value()
  File "/usr/lib/python2.7/uuid.py", line 129, in __init__
    raise TypeError('need one of hex, bytes, bytes_le, fields, or int')
TypeError: need one of hex, bytes, bytes_le, fields, or int

Answer 1

错误与 user_id 的默认值有关。将默认设置为 uuid.uuid4，这将生成 UUID 对象。

class User(db.DynamicDocument):
    user_id = db.UUIDField(primary_key=True, required=True, default=uuid.uuid4)
    ...