代码之家 › 专栏 › 技术社区 › Souvik Ray

Django抛出“禁止直接分配到多对多集的前端。”错误

manytomanyfield python-3.x django

Souvik Ray · 技术社区 · 6 年前

我在Django有两个模特 Users 和 Contexts 。我已将模型定义如下

class User(models.Model):
    userId = models.PositiveIntegerField(null = False)
    pic = models.ImageField(upload_to=getUserImagePath,null=True)
    Email = models.EmailField(null = True)

class Contexts(models.Model):
    context_name = models.CharField(max_length=50)
    context_description = models.TextField()
    context_priority = models.CharField(max_length=1)
    users = models.ManyToManyField(User, related_name='context_users')

现在我得到一个post请求,其中包含以下json

{
"user" : 12,
"action" : "add",
"context_name": "Network debug",
"context_description" : "Group for debugging network issues",
"context_priority": "L"
}

我想在 语境 下表是我要做的

from django.shortcuts import render
from django.views.decorators.csrf import csrf_exempt
from django.http import HttpResponse
import json
from .models import *
import json


@csrf_exempt
def context_operation(request):
    if request.method == "POST":
        user_request = json.loads(request.body.decode('utf-8'))
        try:
            if user_request.get("action") == "add":
                conv = Contexts.objects.create(
                    context_name=user_request.get("context_name"),
                    context_description=user_request.get("context_description"),
                    context_priority=user_request.get("context_priority"),
                    users=user_request.get("user")
                )
                conv.save()
        except Exception as e:
            print("Context saving exception", e)
            return HttpResponse(0)
        return HttpResponse(1)

在这里,我试图基于json请求中的action字段添加一个上下文。 语境 模型,领域 users 与 User 但是当我试图将值保存到 Contexts table ,我收到以下错误

Context saving exception Direct assignment to the forward side of a many-to-many set is prohibited. Use users.set() instead.

基于 this StackOverflow post ,我试着这样做:

users=User.objects.add(user_request.get("user"))

但我还是收到了同样的错误。我做错什么了?

1 回复 | 直到 6 年前

Daniel Roseman 6 年前

错误应该是清楚的;不能直接分配给多对多字段。创建项目后执行此操作。

conv = Contexts.objects.create(
    context_name=user_request.get("context_name"),
    context_description=user_request.get("context_description"),
    context_priority=user_request.get("context_priority"),
)
conv.users.add(user_request.get("user"))

另外请注意,你不需要打电话 save() 之后 create() 或者添加m2m值。