NOT NULL 约束失败：snippets_choice.post_id答案

【问题标题】：NOT NULL constraint failed: snippets_choice.post_idNOT NULL 约束失败：snippets_choice.post_id
【发布时间】：2020-02-11 14:23:18
【问题描述】：

我在这里尝试使用 POST 方法，但它给我一个错误。

这是 Models.py：

from django.db import models

class Post(models.Model):
    post_text=models.CharField(max_length=200)

    def __str__(self):
        return self.post_text

class Choice(models.Model):
    post=models.ForeignKey(Post, on_delete=models.CASCADE)
    choice_text=models.CharField(max_length=200)
    likes=models.IntegerField(default=0)

    def __str__(self):
        return self.choice_text

这是serializes.py：

from rest_framework import serializers
from snippets.models import Post, Choice

class PostSerializer(serializers.HyperlinkedModelSerializer):
    class Meta:
        model=Post
        fields=['id','post_text']

class ChoiceSerializer(serializers.HyperlinkedModelSerializer):
    class Meta:
        model=Choice
        fields=['id','choice_text','likes']

这是views.py：


from django.shortcuts import render
from rest_framework import generics
from rest_framework.reverse import reverse
from .models import Choice, Post
from django.http import Http404
from rest_framework.views import APIView
from rest_framework.response import Response
from rest_framework import status
from snippets.serializers import ChoiceSerializer, PostSerializer

class PostList(generics.ListCreateAPIView):
    queryset=Post.objects.all()
    serializer_class=PostSerializer
    name='post-list'

class PostDetail(generics.RetrieveUpdateDestroyAPIView):
    queryset=Post.objects.all()
    serializer_class=PostSerializer
    name='post-detail'

class ChoiceList(generics.ListCreateAPIView):
    queryset=Choice.objects.all()
    serializer_class=ChoiceSerializer
    name='choice-list'

class ChoiceDetail(generics.RetrieveUpdateDestroyAPIView):
    queryset=Choice.objects.all()
    serializer_class=ChoiceSerializer
    name='choice-detail'

class ApiRoot(generics.GenericAPIView):
    name='api-root'

    def get(self, request, *args, **kwargs):
        return Response({
        'posts': reverse(PostList.name, request=request),
        'choices': reverse(ChoiceList.name, request=request),
        })

urls.py:

urlpatterns=[
    path('post-list/', views.PostList.as_view(), name='post-list'),
    path('post-list/<int:pk>/', views.PostDetail.as_view()),
    path('choice-list/', views.ChoiceList.as_view(), name='choice-list'),
    path('choice-list/<int:pk>/', views.ChoiceDetail.as_view()),
    path('',views.ApiRoot.as_view(),name=views.ApiRoot.name),
]

当我尝试发帖时：

{ 
    "id":3
    "choice_text": "random text",
    "likes": 0
}

我收到了这个错误：

IntegrityError at /choice-list/
NOT NULL constraint failed: snippets_choice.post_id

如果我提供了 id，为什么会抛出错误？

即使在 Postman 中，它也要求我输入“choice_text”，即使我提供了choice_text。

【问题讨论】：

标签： python django django-rest-framework django-orm

【解决方案1】：

您正在尝试创建一个选项，并且 Choice 模型与具有非空约束的 Post 模型相关，因此请将 post 外键设置为 null

post=models.ForeignKey(Post, on_delete=models.CASCADE)

到

post=models.ForeignKey(Post, on_delete=models.CASCADE, null=True)

或者您必须先创建一个帖子，然后在创建选项时传递帖子 ID

向 /post-list/ 发送请求

{
   "post_text": "Hello World!"
}

它将创建一个带有帖子 ID 的帖子，比如说 post_id = 1

向 /choice-list/ 发送请求

{ 
    "choice_text": "random text",
    "likes": 0,
    "post": 1
}

【讨论】：