Question

我在Django Users和Contexts中有两个模型。我定义了以下模型

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')

现在我得到一个包含以下JSON的POST请求

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

我想在Contexts表中创建一条记录。下面是我要做的事情

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字段添加上下文。如您所见，在Contexts模型中，字段users与{ {1}}模型。但是，当我尝试将值保存到User时，出现以下错误

Contexts table

基于this StackOverflow post，我尝试执行以下操作：

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

但是我仍然收到相同的错误。我在做什么错了？

Answer 1

错误应该很清楚；您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"))

还请注意，您无需在save()或添加m2m值之后调用create()。

Django抛出“禁止直接分配给多对多集的前端。”错误

1 个答案: