为什么 Sales 字段没有到达前面，即使它们已添加到序列化程序中

楷模

class Product(models.Model):
    name = models.CharField(max_length=150, db_index=True,
                            verbose_name='Название')
    slug = models.SlugField(max_length=150, db_index=True)
    price = models.DecimalField(max_digits=10, decimal_places=2, 
                                verbose_name='Цена')
    category = models.ForeignKey(Category, 
                                 related_name='category',
                                 null=True,
                                 blank=True,
                                 verbose_name='Категория',
                                 on_delete=models.CASCADE,
                                 )
    sales = models.ManyToManyField(Sale, 
                                   related_name='sales',
                                   verbose_name='Скидка',
                                   blank=True
                                   )

class Sale(models.Model):
    name = models.CharField(max_length=150)
    description = models.CharField(max_length=255)
    percent = models.IntegerField(verbose_name='Процент')

    class Meta:
        ordering = ('name', 'percent')
        verbose_name = 'Скидка'
        verbose_name_plural = 'Скидки'

    def __str__(self):
        return self.name

序列化器

class SaleSerializer(serializers.ModelSerializer):
    class Meta:
        model = Sale
        fields = ['name', 'percent']


class ProductSerializer(serializers.ModelSerializer):
    category = CategorySerializer(read_only=True)
    sale = SaleSerializer(many=True, read_only=True)

    class Meta:
        model = Product
        fields = ['slug', 'name', 'price', 'sale',
                  'category']

        lookup_field = 'slug'

看法

class ProductsBySales(ListAPIView):
    serializer_class = ProductSerializer
    filterset_class = ProductSaleFilter

    def get_queryset(self):
        return Product.objects.exclude(sales=None)

前面给出的对象：

[
    {
        "slug": "8",
        "name": "8",
        "price": "1.00",
        "category": {
            "name": "phones",
            "parental_category": null
        },
    },