Django:错误：“重复的键值违反了唯一约束”

Question

在为我的网站创建新对象时，我必须使用s3保存图像

我有一个用于保存图像的代码，我在模型的保存方法中使用了该代码

当我使用django管理面板时，我可以轻松地创建我的对象而不会出现任何错误

当我发送数据而不添加图像时，它也能很好地工作

但是，当我试图通过视图创建对象时，会出现以下错误：Error: 'duplicate key value violates unique constraint « store_shop_pkey »' DETAIL: key (id)=(37) already exists

我认为在序列化程序的create方法中，我尝试保存对象两次：一次用于图像，一次用于对象的其余键

我不知道如何解决这个问题

与PUT方法配合使用效果良好

这是我的密码：

models.py:

class Shop(models.Model):

    name = models.CharField(max_length=255)
    category = models.ForeignKey(ShopCategory, on_delete=models.SET_NULL, null=True, blank=True)
    description = models.TextField(blank=True, null=True)
    path = models.CharField(max_length=255, unique=True, null=True, blank=True) # Set a null and blank = True for serializer
    mustBeLogged = models.BooleanField(default=False)
    deliveries = models.FloatField(validators=[MinValueValidator(0),], default=7)
    message = models.TextField(null=True, blank=True)
    banner = models.ImageField(null=True, blank=True)

    def save(self, *args, **kwargs):
        try:
            """If we want to update"""
            this = Shop.objects.get(id=self.id)
            if self.banner:
                image_resize(self.banner, 300, 300)
                if this.banner != self.banner:
                    this.banner.delete(save=False)
            else:
                this.banner.delete(save=False)
        except:
            """If we want to create a shop"""
            if self.banner:
                image_resize(self.banner, 300, 300)
        super().save(*args, **kwargs)

    def delete(self):
        self.banner.delete(save=False)
        super().delete()
        
    def __str__(self):
        return self.name

utils.py:

def image_resize(image, width, height):
    # Open the image using Pillow
    img = Image.open(image)
    # check if either the width or height is greater than the max
    if img.width > width or img.height > height:
        output_size = (width, height)
        # Create a new resized “thumbnail” version of the image with Pillow
        img.thumbnail(output_size)
        # Find the file name of the image
        img_filename = Path(image.file.name).name
        # Spilt the filename on “.” to get the file extension only
        img_suffix = Path(image.file.name).name.split(".")[-1]
        # Use the file extension to determine the file type from the image_types dictionary
        img_format = image_types[img_suffix]
        # Save the resized image into the buffer, noting the correct file type
        buffer = BytesIO()
        img.save(buffer, format=img_format)
        # Wrap the buffer in File object
        file_object = File(buffer)
        # Save the new resized file as usual, which will save to S3 using django-storages
        image.save(img_filename, file_object)

views.py:

class ShopList(ShopListView):
    """Create shop"""
    def post(self, request):
        """For admin to create shop"""
        serializer = MakeShopSerializer(data=request.data)
        if serializer.is_valid():
            serializer.save()
            return Response(serializer.data)
        return Response(serializer.errors)

serializers.py:

class MakeShopSerializer(serializers.ModelSerializer):
    class Meta:
        model = Shop
        fields = '__all__'

    def create(self, validated_data):
        # validated_data.pop('path')
        path = validated_data["name"].replace(" ", "-").lower()
        path = unidecode.unidecode(path)
        unique = False
        while unique == False:
            if len(Shop.objects.filter(path=path)) == 0:
                unique = True
            else:
                # Generate a random string
                char = "abcdefghijklmnopqrstuvwxyz"
                path += "-{}".format("".join(random.sample(char, 5)))
        shop = Shop.objects.create(**validated_data, path=path)
        shop.save()
        return shop
    
    def update(self, instance, validated_data):
        #You will have path in validated_data
        #And you may have to check if the values are null
        return super(MakeShopSerializer, self).update(instance, validated_data)

最后，这是我发送的数据：

提前感谢您的帮助

Answer 1

模型的唯一键是path，所以在序列化程序的create函数中

shop = Shop.objects.create(**validated_data, path=path)，尝试创建新模型。 考虑您尝试添加的第二个实例具有与前一个实例相同的路径，在这种情况下，您会得到这个错误，因为^ {CD1}}应该是唯一的，并且您试图添加具有DBMS拒绝的相同值的另一个模型。 你可以尝试的一件事是， 创建或更新实例。如果您可以在第二个实例与前一个实例具有相同路径时更新该实例，则使用

Shop.objects.update_or_create(path=path,
                        defaults=validated_data)

否则

如果您的模型不能仅通过使用path字段保持唯一，请尝试添加唯一约束。 django documentation

Answer 2

下一行主键可能有问题：

shop = Shop.objects.create(**validated_data, path=path)

您可以尝试逐个放置每个属性，如下所示：

shop = Shop.objects.create(
name=validated_data['name'],
category=validated_data['category'],
...
path=path)

如果它不能解决您的问题，请在终端上发布更多关于您的错误的信息