Question

我正在制作一个应用程序，分配者可以将任务分配给受让人当我运行服务器并尝试添加任务时，我收到此错误：

NOT NULL约束失败：tasks_tasks.assigner_id

这是我的观点：

from rest_framework import viewsets, permissions
from .models import Tasks
from .serializers import TasksSerializer, UserSerializer
from django.contrib.auth.models import User


class UserViewSet(viewsets.ReadOnlyModelViewSet):
    queryset = User.objects.all()
    serializer_class = UserSerializer


class TasksViewSet(viewsets.ModelViewSet):
    queryset = Tasks.objects.all()
    serializer_class = TasksSerializer
    permission_classes = (permissions.IsAuthenticatedOrReadOnly,)

    def prefrom_create(self, serializer):
        serializer.save(self, assigner=self.request.user)

这是我的serializers.py

from rest_framework import serializers
from .models import Tasks
from django.contrib.auth.models import User


class TasksSerializer(serializers.ModelSerializer):
    assigner = serializers.ReadOnlyField(source='assigner.username')

    class Meta:
        model = Tasks
        fields = ('id', 'url', 'title', 'description', 'assigner', 'assignee')


class UserSerializer(serializers.ModelSerializer):
    tasks = serializers.HyperlinkedIdentityField(many=True, view_name='tasks_details', read_only=True)

    class Meta:
        model = User
        fields = ('id', 'url', 'username', 'tasks')

最后是我的models.py：

from django.db import models

class Tasks(models.Model):
    created = models.DateTimeField(auto_now_add=True)
    title = models.CharField(max_length=100)
    description = models.TextField()
    assigner = models.ForeignKey('auth.User', related_name='tasks', on_delete=models.CASCADE)
    assignee = models.ForeignKey('auth.User', related_name='assigned', on_delete=models.CASCADE)

    class Meta:
        ordering = ('created',)

Answer 1

您已将assigner设为包含来源assigner.username的只读字段 - 这是您的问题。我认为你可以通过定义两个字段来解决这个问题，一个是read_only，一个是write_only：

class TasksSerializer(serializers.ModelSerializer):
assigner_name = serializers.ReadOnlyField(source='assigner.username')
assigner = serializers.PrimaryKeyRelatedField(write_only=True, queryset=User.objects.all(), required=True)
class Meta:
    model = Tasks
    fields = ('id', 'url', 'title', 'description', 'assigner', 'assignee', 'assigner_name')

此代码的作用是当序列化程序“正在写入”（反序列化）时，它将接受作为关键字参数assigner传递给save方法的分配器ID。然后，当它将任务序列化为json时，它会查找assigner.name并将其返回到密钥assigner_name下并遗漏assigner。

在视图中，您将主键（而不是整个对象）传递给序列化程序保存方法：

serializer.save(assigner=self.request.user.pk)

rest_framework NOT NULL约束失败：tasks_tasks.assigner_id

1 个答案: