如何在 Django Rest Framework 中使用 ManyToMany 关系与中介模型序列化附加字段？

Question

我正在尝试通过创建中间模型 IngredientAmount 将字段 amount 添加到 Ingredient 模型中。但是我正在为序列化而苦苦挣扎。

响应应如下所示：

"results": [
......
         "ingredients": [
          {
            "id": 0,
            "name": "Potato",
            "measurement_unit": "kg",
            "amount": 1
             }
         ],
....
]

我正在使用 IngredientAmountSerializer(serializers.ModelSerializer)，但 Django 说我在 'Ingredient' 对象中并且它没有属性 'amount'.

我做错了什么？

型号

    class Ingredient(models.Model):
    name = models.CharField(max_length=200)
    measurement_unit = models.CharField(max_length=200)

    class Meta:
        ordering = ['id']

    def __str__(self):
        return self.name


class IngredientAmount(models.Model):
    ingredient = models.ForeignKey(Ingredient, on_delete=models.CASCADE,
                                   related_name='ingredient_amount')
    recipe = models.ForeignKey('Recipe', on_delete=models.CASCADE,
                               related_name='ingredient_amount')
    amount = models.SmallIntegerField(
        validators=(
            validators.MinValueValidator(
                1, 'add amount'),))


class Recipe(models.Model):
    author = models.ForeignKey(User, on_delete=models.CASCADE)
    ingredients = models.ManyToManyField(
        Ingredient, through=IngredientAmount,
        through_fields=('recipe', 'ingredient', ),
        )
    tags = models.ManyToManyField(Tag, blank=True, related_name='recipe')
    image = models.ImageField()
    name = models.CharField(max_length=200)
    text = models.TextField()
    cooking_time = models.PositiveSmallIntegerField(
        validators=(
            validators.MinValueValidator(1, message='choose time'),
                   ),
                )

序列化程序

class IngredientAmountSerializer(serializers.ModelSerializer):
    name = serializers.CharField(source='ingredient.name', read_only=True)
    measurement_unit = serializers.IntegerField(source='ingredient.measurement_unit', read_only=True)
    class Meta:
        model = IngredientAmount
        fields = ('id', 'name', 'measurement_unit', 'amount' )


class RecipeSerializer(serializers.ModelSerializer):
    author = AuthorSerializer()
    tags = TagSerializer(read_only=True, many=True)
    image = Base64ImageField(required=True)
    ingredients = IngredientAmountSerializer( read_only=True, many=True)

    class Meta:
        model = Recipe
        fields = ('id', 'tags', 'author', 'name', 'image', 'text',
                  'cooking_time', 'ingredients')

Answer 1

我猜问题是，您正在尝试使用 IngredientAmountSerializer 序列化 Ingredient 模型，而其中 Meta 模型是 IngredientAmount，而不是 Ingredient.

更新：如果你想序列化IngredientAmount，尝试使用source

class RecipeSerializer(serializers.ModelSerializer):
    ...
    ingredients = IngredientAmountSerializer(source='ingredientamount_set', read_only=True, many=True)

如何在 Django Rest Framework 中使用 ManyToMany 关系与中介模型序列化附加字段？

How to Serialize an additional field using ManyToMany relationship with intermediary model in Django Rest Framework?

python

django-models

django-related-manager

django-serializer

django-rest-framework