500错误：“timeline\u id”列中的null值违反notnull约束

Question

我目前是一名学生，正在尝试用python/django和React创建一个全栈web应用程序。在构建后端时，我遇到了一个问题，在发布包含关联的对象时，响应负载和数据库之间的关联id丢失。我知道状态正在按其应该的方式更新，并且可以毫无问题地创建在后端不使用关联的其他对象。我假设我的错误一定是在我所做的模型或序列化程序中的某个地方，但到目前为止我还没有找到它

500错误消息：

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

我的序列化程序：

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 repo: https://github.com/dantehollo/world_builder_site

我在linux上使用Python3.6.8（ubuntu 18.04.3）

我尽量说得具体和简短。如果有什么遗漏让我知道，我会尽快张贴我看到的要求。非常感谢您对我们的帮助，为什么会这样，以及如何避免再次发生，谢谢

Answer 1

根据Event模型，timeline属性（也是外键）是必需的，不能为null。您忘了将这个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ValidationError，您必须包含它