Mongoengine：如何更新现有文档的特定字段？

Question

我有一个现有的 mongo 文档，该文档已通过 REST API 公开。 API 请求将包含文档中的某些字段，如果该字段为空，则需要使用新值更新或在其中插入新值。如何对现有 mongo 引擎文档的字段执行更新？我正在使用棉花糖-mongo引擎在烧瓶上进行序列化。

我面临的问题是，如果请求有效负载中缺少某个字段，则在使用剩余字段调用更新时，kwargs 会导致将缺少的字段设置为 None。如何仅更新或插入有效负载中给定的字段？

Answer 1

如果您只想更新一个文档，您可以使用保存方法。我就是做这个的。如果文档已经存在，它会更新字段而不是创建新文档。

car = Car.objects(pk=car_id) # return a queryset
if car:     
    car = car.get(pk=car_id) # return an object from queryset
    car.make = requestData['make']
    car.model = requestData['model']
    car.mileage = requestData['mileage']
    car.save()

如果您想更新很多文档，我建议您查看用户指南的 atomic updates 部分。

有点像~

Car.objects(param="param to filter by").update(set__param=newParam)

"set"后跟两个下划线是修饰符。我在上面链接的指南中提供了更多修饰符。

Answer 2

约瑟夫的回答是好的。但另一个答案不会伤害呃！

下面是我如何使用 flask-mongoengine 更新我的文档

实际代码：

Game.objects(id = _id).update(
        set__kickoff = request_json.get('kickoff'),
        set__gameid = request_json.get('gameid'),
        set__home_team = request_json.get('home_team'),
        set__away_team = request_json.get('away_team'),
        set__home_win = request_json.get('home_win'),
        set__draw = request_json.get('draw'),
        set__away_win = request_json.get('away_win'),
        set__sport = request_json.get('sport')
        )

Game class : 

    import datetime
    flask_mongoengine import BaseQuerySet, MongoEngine
    db = MongoEngine()

    class Game(db.Document):
    kickoff  = db.DateTimeField(required=True)
    added_on  = db.DateTimeField(default=datetime.datetime.utcnow)
    gameid = db.FloatField(required=True)     
    home_team = db.StringField(required=True)
    home_win = db.FloatField(required=True)    
    draw = db.FloatField(required=True)
    away_win = db.FloatField(required=True)
    away_team = db.StringField(required=True)
    sport = db.StringField(required=True) 
    meta = {
        'collection':'games',
        'queryset_class': BaseQuerySet
    }

PS : 记得在 python

中缩进代码

此外，我注意到您在问题中标记了 Marshmallow。在这里，来自他们官方 git repo here

的示例

First we need a Mongoengine Document:

import mongoengine as me

class Task(me.EmbeddedDocument):
    content = me.StringField(required=True)
    priority = me.IntField(default=1)


class User(me.Document):
    name = me.StringField()
    password = me.StringField(required=True)
    email = me.StringField()
    tasks = me.ListField(me.EmbeddedDocumentField(Task))

Great ! Now it's time for the Marshmallow Schema. To keep things DRY, we use marshmallow-mongoengine to do the mapping:

import marshmallow_mongoengine as ma

class UserSchema(ma.ModelSchema):
    class Meta:
        model = User

Finally it's time to use our schema to load/dump documents:First let's create a document

user_schema = UserSchema()
u, errors = user_schema.load({"name": "John Doe", "email": 
      "jdoe@example.com", "password": "123456","tasks": [{"content": "Find a 
      proper password"}]})
u.save()

If the document already exists, we can update it using update

u
u2, errors = user_schema.update(u, {"name": "Jacques Faite"})
>>> u2.name
"Jacques Faite"

Mongoengine：如何更新现有文档的特定字段？

Mongoengine : How to update specific fields of an existing document?

flask

mongoengine

marshmallow