当前不直接支持此功能，因为MongoEngine仅支持mongodb的扩展json语法。
mongoengine所做的所有工作都是使用pymongo
json_utils来转储数据。没有理由不能明确使用它，例如：
from bson import json_util class Inbox(db.document): from_user = db.ReferenceField(User, required=True) subject = db.StringField(max_length=255, required=True) created_at = db.DateTimeField(default=datetime.now) messages = db.ListField(db.EmbeddeddocumentField(Message)) def to_json(self): data = self.to_mongo() // get the pymongo representation of the document data["from_user"] = {"User": {"username": self.from_user.username}} return json_util.dumps(data) User.drop_collection() ... Inbox.drop_collection() ross = User(username="Ross").save() Inbox(from_user=ross, subject="Mongoengine should make json easier").save() doc = Inbox.objects.only('from_user', 'subject', 'created_at').get() print doc.to_json() {"_id": {"$oid": "538c3d71c3d384172fe35393"}, "from_user": {"User": {"username": "Ross"}}, "subject": "Mongoengine should make json easier", "created_at": {"$date": 1401703297198}, "messages": []}更新
带有自定义查询集的示例：
from bson import json_util class CustomQuerySet(QuerySet): def to_json(self): return "[%s]" % (",".join([doc.to_json() for doc in self])) class Inbox(document): from_user = ReferenceField(User, required=True) subject = StringField(max_length=255, required=True) created_at = DateTimeField(default=datetime.now) messages = ListField(EmbeddeddocumentField(Message)) meta = {'queryset_class': CustomQuerySet} def to_json(self): data = self.to_mongo() data["from_user"] = {"User": {"username": self.from_user.username}} return json_util.dumps(data) ... ipdb> Inbox.objects.only('from_user', 'subject', 'created_at').to_json() '[{"_id": {"$oid": "538d84cbc3d3843eeeb5dbbe"}, "from_user": {"User": {"username": "Ross"}}, "subject": "Mongoengine should make json easier", "created_at": {"$date": 1401787099246}, "messages": []}]'
