Django REST 框架 : save related models in ModelViewSet

Question

我正在尝试弄清楚如何使用 Django REST 框架保存相关模型。
在我的应用程序中，我有一个模型 Recipe有 2 个相关型号:RecipeIngredient和 RecipeStep .一个 Recipe对象必须至少有 3 个相关的 RecipeIngredient和 3 RecipeStep .在引入 REST 框架之前，我使用的是 Django CreateView有两个表单集，保存过程如下(遵循来自 form_valid() 的代码):

def save_formsets(self, recipe):
    for f in self.get_formsets():
        f.instance = recipe
        f.save()

def save(self, form):
    with transaction.atomic():
        recipe = form.save()
        self.save_formsets(recipe)
    return recipe

def formsets_are_valid(self):
        return all(f.is_valid() for f in self.get_formsets())

def form_valid(self, form):
    try:
        if self.formsets_are_valid():
            try:
                return self.create_ajax_success_response(form)
            except IntegrityError as ie:
                return self.create_ajax_error_response(form, {'IntegrityError': ie.message})
    except ValidationError as ve:
        return self.create_ajax_error_response(form, {'ValidationError': ve.message})
    return self.create_ajax_error_response(form)

现在我有我的 RecipeViewSet :

class RecipeViewSet(ModelViewSet):
    serializer_class = RecipeSerializer
    queryset = Recipe.objects.all()
    permission_classes = (RecipeModelPermission, )

使用 RecipeSerializer :

class RecipeSerializer(serializers.ModelSerializer):
    class Meta:
        model = Recipe
        fields = (
            'name', 'dish_type', 'cooking_time', 'steps', 'ingredients'
        )

    ingredients = RecipeIngredientSerializer(many=True)
    steps = RecipeStepSerializer(many=True)

这些是相关的序列化程序:

class RecipeIngredientSerializer(serializers.ModelSerializer):
    class Meta:
        model = RecipeIngredient
        fields = ('name', 'quantity', 'unit_of_measure')

class RecipeStepSerializer(serializers.ModelSerializer):
    class Meta:
        model = RecipeStep
        fields = ('description', 'photo')

现在......我应该如何验证相关模型( RecipeIngredient 和 RecipeStep )并在 RecipeViewSet 时保存它们的 create()方法被调用？ ( is_valid() 中的 RecipeSerializer 实际上忽略了嵌套关系并仅报告与主模型 Recipe 相关的错误)。
目前我试图覆盖 is_valid() RecipeSerializer 中的方法，但不是那么简单......有什么想法吗？

Answer 1

这周我正在处理类似的问题，我发现 django rest framework 3 实际上支持嵌套可写序列化(http://www.django-rest-framework.org/topics/3.0-announcement/#serializers 在可写嵌套序列化子章节中。)

我不确定嵌套序列化器是否可写为默认值，所以我声明了它们:

ingredients = RecipeIngredientSerializer(many=True, read_only=False)
steps = RecipeStepSerializer(many=True, read_only=False)

你应该在 RecipeSerializer 中重写你的创建方法:

class RecipeSerializer(serializers.ModelSerializer):
    ingredients = RecipeIngredientSerializer(many=True, read_only=False)
    steps = RecipeStepSerializer(many=True, read_only=False)

    class Meta:
        model = Recipe
        fields = (
            'name', 'dish_type', 'cooking_time', 'steps', 'ingredients'
        )

    def create(self, validated_data):
        ingredients_data = validated_data.pop('ingredients')
        steps_data = validated_data.pop('steps')
        recipe = Recipe.objects.create(**validated_data)
        for ingredient in ingredients_data:
            #any ingredient logic here
            Ingredient.objects.create(recipe=recipe, **ingredient)
        for step in steps_data:
            #any step logic here
            Step.objects.create(recipe=recipe, **step)
        return recipe

如果这个结构 Step.objects.create(recipe=recipe, **step) 不起作用，也许你必须从steps_data/成分数据中分别选择代表每个字段的数据。

这是指向我之前(已实现的)堆栈问题/答案的链接:How to create multiple objects (related) with one request in DRF?