基于此tutorial :
from mongoengine import *
connect('tumblelog')
class User(Document):
email = StringField(required=True, unique=True)
first_name = StringField(max_length=50)
last_name = StringField(max_length=50)
class Comment(EmbeddedDocument):
content = StringField()
name = StringField(max_length=120)
class Post(Document):
title = StringField(max_length=120, required=True)
author = ReferenceField(User, reverse_delete_rule=CASCADE)
tags = ListField(StringField(max_length=30))
comments = ListField(EmbeddedDocumentField(Comment))
meta = {'allow_inheritance': True}
class TextPost(Post):
content = StringField()
class ImagePost(Post):
image_path = StringField()
class LinkPost(Post):
link_url = StringField()
def main():
john = User(email='<a href="https://stackoverflow.com/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="bad0ded5dffadfc2dbd7cad6df94d9d5d7" rel="noreferrer noopener nofollow">[email protected]</a>', first_name='John', last_name='Doe')
john.save()
john_from_db = User.objects(email='<a href="https://stackoverflow.com/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="650f010a0025001d04081509004b060a08" rel="noreferrer noopener nofollow">[email protected]</a>')
post1 = TextPost(title='Fun with MongoEngine', author = john_from_db)
post1.content = 'Took a look at MongoEngine today, looks pretty cool.'
post1.tags = ['mongodb','mongoengine']
post1.save()
if __name__ == '__main__':
main()
我在 post1.save() 上收到此错误:
mongoengine.base.ValidationError: ValidationError(A ReferenceField only accepts DBRef or documents: ['author'])
我尝试在 ReferenceField 声明中添加 dbref=True/False 选项，但没有解决任何问题。对象 john 是 User 类型，而 john_from_db 是一个 QuerySet。当然，我在这里遗漏了一些东西，如何从数据库获取一个对象并在另一个对象中使用它？
最佳答案
您必须在查询集上调用first()来获取与查询匹配的第一条记录，例如
john_from_db = User.objects(email='<a href="https://stackoverflow.com/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="fe949a919bbe9b869f938e929bd09d9193" rel="noreferrer noopener nofollow">[email protected]</a>').first()
关于python - mongoengine - 使用 QuerySet 作为 ReferenceField，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/14188049/