Django Rest Framework 以一对多关系获取其他相关字段

Question

这是问题产品有多种尺寸，这是多对多的关系

产品

|-------|---------|
|   ID  |  Title  |
|-------|---------|

尺寸

|-------|---------|
|   ID  |  Title  |
|-------|---------|

大小通过

|------|--------------|-----------|---------|
|  ID  |  Product ID  |  Size ID  |  Stock  |
|------|--------------|-----------|---------|

我设法使用 Django Rest Framework 在我的产品 api 中获取尺寸，但我也不知道如何获取库存信息。 这是我的代码

class SizeSerializer(serializers.ModelSerializer):
    class Meta:
        fields = (
            'id',
            'title',
        )
        model = Size



class ProductsSerializer(serializers.ModelSerializer):
    sizes = SizeSerializer(many=True)

    class Meta:
        fields = (
            'url',
            'id',
            'title',
            "sizes",
        )
        model = Products

如果能在这个问题上提供任何帮助，我将不胜感激

模型

class Products(models.Model):
    title = models.CharField(max_length=125)
    sizes = models.ManyToManyField(Size, blank=True, through='SizeThrough')

    class Meta:
        verbose_name_plural = 'Products'
        verbose_name = 'Product'

    def __str__(self):
        return self.title

class SizeThrough(models.Model):
    size = models.ForeignKey(Size, on_delete=models.CASCADE)
    product = models.ForeignKey(Products, on_delete=models.CASCADE)
    stock = models.BooleanField(null=False, default=1)

class Size(models.Model):
    title = models.CharField(max_length=20)

    def __str__(self):
        return self.title

Answer 1

你可以试试这个。也许它有效

class ProductsSerializer(serializers.ModelSerializer):
    sizes = SizeSerializer(many=True)
    stock = serializers.SerializerMethodField()

    def get_stock(self, obj):
         return[(x.stock, x.size) for x in SizeThrough.objects.filter(product=obj)]

    class Meta:
        fields = (
        'url',
        'id',
        'title',
        "sizes",
        "stock",
    )
        model = Products

Answer 2

你应该通过SizeThrough得到Size（你正在尝试相反的事情）：

class SizeSerializer(serializers.ModelSerializer):
    class Meta:
        fields = (
            'id',
            'title',
        )
        model = Size


class SizeThroughSerializer(serializers.ModelSerializer):
    size = SizeSerializer()
    class Meta:
        fields = (
            'stock',
            'size',
        )
        model = SizeThrough


class ProductsSerializer(serializers.ModelSerializer):
    sizes_info = SizeThroughSerializer(source='sizethrough_set', many=True)

    class Meta:
        fields = (
            'url',
            'id',
            'title',
            "sizes_info",
        )
        model = Products