python - 如何在ming中通过_id查找？

Question

我在ming有一个映射类

from ming import Session, create_datastore
from ming import schema
from ming.odm import ODMSession
from ming.odm.mapper import MapperExtension
from ming.odm.property import ForeignIdProperty
from ming.odm.property import FieldProperty, RelationProperty
from ming.odm.declarative import MappedClass
import config

bind = create_datastore(config.DATABASE_NAME)
session = Session(bind)
odm_session = ODMSession(doc_session=session)


class Document(MappedClass):

    class __mongometa__:
        session = odm_session
        name = 'document'

    _id = FieldProperty(schema.ObjectId)

现在，我想对它做一个简单的查询

Document.query.get(_id="51e46f782b5f9411144f0efe")

但它不起作用。文档不是很清楚。我知道在 mongodb shell 中我们必须将 id 包装在 ObjectId 对象中，但我无法让它在 Python 中工作

Answer 1

您应该尝试使用 ObjectId 进行查询

from bson.objectid import ObjectId
Document.query.get(_id=ObjectId('51e46f782b5f9411144f0efe'))

用裸 pymongo

from bson.objectid import ObjectId
from pymongo import Connection
connection = Connection()
db = connection['lenin']
collection = db.document
collection.find_one({'_id': '51e35ee82e3817732b7bf3c1'}) # returns None
collection.find_one({'_id': ObjectId('51e35ee82e3817732b7bf3c1')}) # returns the object