NOT NULL约束失败: snippets_choice.post_id

Question

我试图在这里使用POST方法，但它抛出了一个错误。

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
}

我得到了这个错误：

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

如果我提供了id，为什么会抛出一个错误？

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

Answer 1

您正在尝试创建一个选项，并且choice模型与具有not null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)

至

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

或者您必须首先创建帖子，然后在创建选项时传递帖子id。

POST请求到/post-list/

{
   "post_text": "Hello World!"
}

它将创建一个带有帖子id的帖子，假设post_id =1

POST请求到/choice-list/

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