python - 500 错误 : null value in column "timeline_id" violates not-null constraint

Question

我目前是一名学生，正在尝试使用 python/django 和 React 创建一个全栈网络应用程序。在构建我的后端时，我遇到了一个问题，当发布一个包含关联的对象时，关联的 id 在响应有效负载和数据库之间丢失了。我知道状态正在更新，并且可以毫无问题地创建后端不使用关联的其他对象。我假设我的错误一定是在我制作的模型或序列化器中的某个地方，但到目前为止我还没有找到它。

500 错误信息:

Integrity error at "api/v1/event"
null value in column "timeline_id" violates not-null constraint
DETAIL: failing row contains (index_id, junk_data, junk_data, 1, null)

我的模型:

from django.db import models

class Timeline(models.Model):
    name = models.CharField(max_length=50, default='n/a')

    def __str__(self):
        return self.name


class Event(models.Model):
    name = models.CharField(max_length=25, default='n/a')
    description = models.CharField(max_length=150, default='n/a')
    coordinate = models.IntegerField(default=0)
    timeline = models.ForeignKey(Timeline, on_delete=models.CASCADE, related_name="events")

    def __str__(self):
        return self.name


class Note(models.Model):
    article = models.TextField(default='n/a')
    event  = models.ForeignKey(Event, on_delete=models.CASCADE, related_name='notes')
    # event = models.ManyToManyField(Event)

    def __str__(self):
        return self.article

我的观点:

from rest_framework import viewsets

from .serializers import TimelineSerializer, EventSerializer, NoteSerializer
from .models import Timeline, Event, Note

class TimelineView(viewsets.ModelViewSet):
    queryset = Timeline.objects.all()
    serializer_class = TimelineSerializer

class EventView(viewsets.ModelViewSet):
    queryset = Event.objects.all()
    serializer_class = EventSerializer

class NoteView(viewsets.ModelViewSet):
    queryset = Note.objects.all()
    serializer_class = NoteSerializer

我的序列化器:

from rest_framework import serializers

from .models import Timeline, Note, Event

class NoteSerializer(serializers.ModelSerializer):

    class Meta:
        model = Note
        fields = ('id', 'title', 'article')


class EventSerializer(serializers.ModelSerializer):
    notes = NoteSerializer(many=True, read_only=True)

    class Meta:
        model = Event
        fields = ('id', 'name', 'description', 'coordinate', 'notes')


class TimelineSerializer(serializers.ModelSerializer):
    events = EventSerializer(many=True, read_only=True)

    class Meta:
        model = Timeline
        fields = ('id', 'name', 'events')

链接到 github 仓库: https://github.com/dantehollo/world_builder_site

我在 linux (ubuntu 18.04.3) 上使用 python 3.6.8

我尽量做到具体和简短。如果有任何遗漏，请告诉我，我会在看到请求后立即发布。非常感谢任何有关这是什么、为什么会发生以及如何避免再次发生的帮助，谢谢。

Answer 1

根据您的Event 模型，timeline 属性(也是外键)是必需的，不能为空。而且您忘记将此 timeline 添加到 EventSerializer 的字段中:

class EventSerializer(serializers.ModelSerializer):
    notes = NoteSerializer(many=True, read_only=True)

    class Meta:
        model = Event
        fields = ('id', 'name', 'description', 'coordinate', 'notes', 'timeline')

现在，如果您不在请求中发送 timeline，DRF 将给出您必须包含它的 ValidationError。