我有任务模型:
class Task(models.Model):
name = models.CharField(max_length=200, blank=True)
description = models.TextField(max_length=1000, blank=True)
completed = models.BooleanField(default=False)
date_created = models.DateField(auto_now_add=True)
due_date = models.DateField(null=True, blank=True)
date_modified = models.DateField(auto_now=True)
tasklist = models.ForeignKey(Tasklist, null=True, related_name='tasks', on_delete=models.CASCADE)
tags = models.ManyToManyField(TaskType, related_name='tasks')
和类任务类型(换句话说标签(:
class TaskType(models.Model):
name = models.CharField(max_length=200)
我也有任务序列化程序:
class TaskSerializer(serializers.ModelSerializer):
tags = serializers.SlugRelatedField(many=True, slug_field='name', queryset=TaskType.objects.all())
class Meta:
model = Task
fields = '__all__'
read_only_fields = ('date_created', 'date_modified', 'tasklist')
当我创建一个任务时,要添加一些标签,我需要首先在适当的视图中创建它们,但我希望它们被动态创建。因此,在编辑任务的情况下,我添加了update
方法:
def update(self, request, *args, **kwargs):
instance = self.get_object()
tag_names = request.data.get('tags', [])
for tag_name in tag_names:
tag, created = TaskType.objects.get_or_create(name=tag_name)
instance.tags.add(tag)
serializer = self.serializer_class(instance=instance, data=request.data)
serializer.is_valid(raise_exception=True)
serializer.save()
return Response(serializer.data)
它工作正常,但是当我在创建新任务时添加新标签时,它会失败(400 个错误请求(:
{
"tags": [
"Object with name=%new_tag% does not exist."
]
}
我发现这是在使用它创建 Task 之前创建适当标签对象的好方法,所以我添加了perform_create
方法:
def perform_create(self, serializer):
print('debug')
tag_names = self.request.data.get('tags', [])
for tag_name in tag_names:
tag, created = TaskType.objects.get_or_create(name=tag_name)
list_id = self.kwargs.get('list_id', None)
try:
tasklist = Tasklist.objects.get(pk=list_id)
except Tasklist.DoesNotExist:
raise NotFound()
serializer.save(tasklist=tasklist)
它对我没有帮助,实际上我不确定是否至少调用了perform_create方法,因为我在控制台中没有看到 print('debug'((当我使用现有标签创建任务时,我看到了它(。所以问题是如何更改perform_create方法,以便能够在不先创建标签的情况下创建新任务。
首先,您无需在视图方法中手动add
标签。序列化程序将为您完成此操作。
其次,更新模型时使用update
方法。创建时,您需要覆盖create
方法,perform_create
有效,但发生得太晚了:
def create(self, request, *args, **kwargs):
tag_names = request.data.get('tags', [])
for tag_name in tag_names:
TaskType.objects.get_or_create(name=tag_name)
serializer = self.serializer_class(data=request.data)
serializer.is_valid(raise_exception=True)
serializer.save()
return Response(serializer.data)
第三,创建新标记后,调用super().*method*
,让框架为您完成工作:
def update(self, request, *args, **kwargs):
tag_names = request.data.get('tags', [])
for tag_name in tag_names:
TaskType.objects.get_or_create(name=tag_name)
return super().update(request, *args, **kwargs)
def create(self, request, *args, **kwargs):
tag_names = request.data.get('tags', [])
for tag_name in tag_names:
TaskType.objects.get_or_create(name=tag_name)
return super().create(request, *args, **kwargs)
如果您计划使用 PATCH 方法,还需要添加partial_update
方法,因此最好重写序列化程序的 to_internal_value
方法,而不是其中的每一个方法:
class TaskSerializer(serializers.ModelSerializer):
tags = serializers.SlugRelatedField(
many=True, slug_field='name', queryset=TaskType.objects.all())
class Meta:
model = Task
fields = '__all__'
read_only_fields = ('date_created', 'date_modified', 'tasklist')
def to_internal_value(self, data):
for tag_name in data.get('tags', []):
TaskType.objects.get_or_create(name=tag_name)
return super().to_internal_value(data)
尝试像这样编辑视图,
def update(self, request, *args, **kwargs):
instance = self.get_object()
tag_names = request.data.get('tags', [])
serializer = self.serializer_class(instance=instance, data=request.data)
if serializer.is_valid(raise_exception=True)
new_object = serializer.save()
if new_object:
for tag_name in tag_names:
tag, created = TaskType.objects.get_or_create(name=tag_name)
new_object.tags.add(tag)
return Response(serializer.data)