我在视图集中解析request.data时遇到问题。我有一个模型,可以根据产品添加多个图像。
我想从传入数据中分割image,将产品数据发送到ProductSerializer,然后将image发送到其使用产品数据进行序列化并保存。
我有两个模型,就像这样:
def Product(models.Model):
name = models.CharField(max_length=20)
color = models.ForeignKey(Color, on_delete=models.CASCADE)
def Color(models.Model):
name = models.CharField(max_length=15)
def Image(models.Model):
product = models.ForeignKey(Product, on_delete=models.CASCADE)
image = models.ImageField(upload_to='product_pics/')
我要发送到Product的请求(127.0.0.1:8000/products/)就像这样:
{
"name": "strawberry",
"color": {
"name": "red"
},
"productimage_set": [
{"image": "<some_encode_image_data>"}
]
}
序列化器没有什么特别的,它只是提取标签链接,所以我没有编写它。如何发送multipart / form-data,如何在视图集中进行解析?或解决方案是什么?
如果我没有正确理解,只需创建一个ImageSerializer并将其附加到ProductSerializer。像这样的东西:
ImageSerializer(serializers.ModelSerializer):
#attrs
ProductSerializer(serializers.ModelSerializer):
productimage_set = ImageSerializer(read_only=True, many=True)
您可以在序列化程序更新/创建方法中分割图像。将您的发布数据=> productimage_set更改为image_set。
ProductSerializer(serializers.ModelSerializer):
image_set = ImageSerializer(read_only=True, many=True)
class Meta:
model = Product
fields = ('name', 'color', 'image_set')
def update(self, instance, validated_data):
image = validated_data.pop('image_set', None)
# if you want you can send image another serializer here.
instance.name = validated_data['name']
instance.save()
return instance
我开发了一个解决方案。使用邮递员,我发送了包含多个图像,单个和嵌套数据的multipart / form-data。
[在我的模型文件中,我将Tags模型添加为ManyToManyField作为示例,并添加了django-taggit。 form-data将类似于图片。
和models.py
class Product(models.Model):
name = models.CharField(max_length=20, blank=True)
tags = models.ManyToManyField(Tags)
taggit = TaggableManager(blank=True)
class ProductImage(models.Model):
product = models.ForeignKey(Product, on_delete=models.CASCADE)
image = models.ImageField(upload_to='image_path/', null=True, blank=True)
class Tags(models.Model):
name = models.CharField(max_length=15, blank=True)
首先,第一个数据未正确解析。为了解决这个问题,并借助answer,我创建了此自定义parser:
class MultipartJsonParser(parsers.MultiPartParser):
def parse(self, stream, media_type=None, parser_context=None):
result = super().parse(
stream,
media_type=media_type,
parser_context=parser_context
)
data = {}
for key, value in result.data.items():
if type(value) != str:
data[key] = value
continue
if '{' in value or "[" in value:
try:
data[key] = json.loads(value)
except ValueError:
data[key] = value
else:
data[key] = value
return parsers.DataAndFiles(data, result.files)
现在我们可以使用此解析器和Django REST内置JSONParser解析数据。现在是时候构建我们的viewsets。
class ProductViewSet(ModelViewSet):
queryset = Product.objects.all()
serializer_class = ProductSerializer
parser_classes = [MultipartJsonParser, JSONParser]
def get_serializer_context(self):
context = super(ProductViewSet, self).get_serializer_context()
# appending extra data to context
if len(self.request.FILES) > 0:
context.update({
'included_images': self.request.FILES
})
return context
def create(self, request, *args, **kwargs):
# Validating images with its own serializer, but not creating.
# The adding process must be through Serializer.
try:
image_serializer = ProductImageSerializer(data=request.FILES)
image_serializer.is_valid(raise_exception=True)
except Exception:
raise NotAcceptable(
detail={
'message': 'Upload a valid image. The file you uploaded was either not '
'an image or a corrupted image.'}, code=406)
# the rest of method is about the product serialization(with extra context),
# validation and creation.
serializer = self.get_serializer(data=request.data)
serializer.is_valid(raise_exception=True)
self.perform_create(serializer)
headers = self.get_success_headers(serializer.data)
return Response(serializer.data, status=status.HTTP_201_CREATED, headers=headers)
class ProductImageViewSet(ModelViewSet):
queryset = ProductImage.objects.all()
serializer_class = ProductImageSerializer
class TagsViewSet(ModelViewSet):
queryset = Tags.objects.all()
serializer_class = TagsSerializer
让我们在这里检查。正如我在评论中提到的,图像文件将包含在request.FILES中。因此,我首先将数据发送到ProductImageSerializer并进行了验证。如果发生验证错误,该过程将停止,API将发送一条错误消息作为响应。然后,我将图像信息连同附加在get_serializer_context方法中的上下文信息一起发送到ProductSerializer。
我们已经完成了create
方法,其他细节都写在了代码上。最后,serializer.py
from django.forms import ImageField as DjangoImageField class TagsSerializer(HyperlinkedModelSerializer): class Meta: model = Tags fields = ['url', 'pk', 'name'] class ProductImageSerializer(HyperlinkedModelSerializer): class Meta: model = ProductImage fields = ['url', 'pk', 'product', 'image'] # attention!!! if you not use this bottom line, # it will show error like "product required" and # indirectly our validation at ProductViewSet will raise error. extra_kwargs = { 'product': {'required': False} } # we created Object-level custom validation because validation not working correctly. # when ProductImageSerializer get single image, everything just fine but # when it get multiple image, serializer is just passing all the files. def validate(self, attrs): default_error_messages = { 'invalid_image': 'Upload a valid image. The file you uploaded was either not an image or a corrupted image.', } # in here we're verifying image with using django.forms; Pillow not necessary !! for i in self.initial_data.getlist('image'): django_field = DjangoImageField() django_field.error_messages = default_error_messages django_field.clean(i) return attrs class ProductSerializer(HyperlinkedModelSerializer, TaggitSerializer): tags = TagsSerializer(allow_null=True, many=True, required=False) # you can delete this line. If you delete it, it will appear as url in response. productimage_set = ProductImageSerializer(allow_null=True, many=True, required=False) taggit = TagListSerializerField(allow_null=True, required=False) class Meta: model = Product fields = ['url', 'pk', 'name', 'tags', 'taggit', 'productimage_set'] def create(self, validated_data): # create product try: product_obj = Product.objects.create( name=validated_data['name'] ) except Exception: raise NotAcceptable(detail={'message': 'The request is not acceptable.'}, code=406) if 'included_images' in self.context: # checking if key is in context images_data = self.context['included_images'] for i in images_data.getlist('image'): ProductImage.objects.create( product=product_obj, image=i ) # pop taggit and create if 'taggit' in validated_data: taggit_data = validated_data.pop('taggit') for taggit_data in taggit_data: taggit_obj, created = Tag.objects.get_or_create(name=taggit_data) product_obj.taggit.add(taggit_obj) # pop tags and create if 'tags' in validated_data: tags_data = validated_data.pop('tags') for tags_data in tags_data: for i in tags_data.items(): tags_obj, created = Tags.objects.get_or_create(name=i[1]) product_obj.tags.add(tags_obj) return product_obj
那么这里发生了什么?为什么我们为图像创建额外的验证?尽管我不知道为什么,但是ImageSerializer仅对单个文件进行正确的验证。如果您尝试上传两个文件,甚至可以在图片旁边放一个电影,验证将无法进行。为了防止这种情况,我们使用django的内置形式依次验证了图片;更改.mp3的格式并将其设置为.jpg,尝试上传大文件,但它们均无法正常工作。进行验证的是纯django。其他详细信息在代码中。
如果您按照我所说的去做,那么响应将是这样的:
我认为这会使大多数邮递员
用户感到高兴。希望对您有所帮助。如果有什么引起您的注意,请在评论中开会。