在Django的REST框架中介模型序列化多对多关系

Question

我遇到了一些麻烦，通过参数序列化多对多关系与在DRF3

非常基本上我有配方和成分，通过指定的中间模型相结合数量和单位使用的特定成分。

这是我的模型：

from django.db import models 
from dry_rest_permissions.generics import authenticated_users, allow_staff_or_superuser 
from core.models import Tag, NutritionalValue 
from usersettings.models import Profile 

class IngredientTag(models.Model): 
    label = models.CharField(max_length=255) 

    def __str__(self): 
     return self.label 


class Ingredient(models.Model): 
    recipe = models.ForeignKey('Recipe', on_delete=models.CASCADE) 
    ingredient_tag = models.ForeignKey(IngredientTag, on_delete=models.CASCADE) 
    amount = models.FloatField() 
    unit = models.CharField(max_length=255) 


class RecipeNutrition(models.Model): 
    nutritional_value = models.ForeignKey(NutritionalValue, on_delete=models.CASCADE) 
    recipe = models.ForeignKey('Recipe', on_delete=models.CASCADE) 
    amount = models.FloatField() 


class Recipe(models.Model): 
    name = models.CharField(max_length=255) 
    ingredients = models.ManyToManyField(IngredientTag, through=Ingredient) 
    tags = models.ManyToManyField(Tag, blank=True) 
    nutritions = models.ManyToManyField(NutritionalValue, through=RecipeNutrition) 
    owner = models.ForeignKey(Profile, on_delete=models.SET_NULL, blank=True, null=True) 

    def __str__(self): 
     return self.name 

而这些都是目前我的串行：

from recipes.models import Recipe, IngredientTag, Ingredient 
from rest_framework import serializers 

class IngredientTagSerializer(serializers.ModelSerializer): 
    class Meta: 
     model = IngredientTag 
     fields = ('id', 'label') 

class IngredientSerializer(serializers.ModelSerializer): 
    class Meta: 
     model = Ingredient 
     fields = ('amount', 'unit') 

class RecipeSerializer(serializers.ModelSerializer): 
    class Meta: 
     model = Recipe 
     fields = ('id', 'url', 'name', 'ingredients', 'tags', 'nutritions', 'owner') 
     read_only_fields = ('owner',) 
     depth = 1 

我如此搜查和网络了不少，但我想不通出来。如果有人能指引我走向正确的方向，那将会很棒。

我可以得到配料清单中返回，像这样：

{ 
    "count": 1, 
    "next": null, 
    "previous": null, 
    "results": [ 
     { 
      "id": 1, 
      "url": "http://localhost:8000/recipes/1/", 
      "name": "Hallo recept", 
      "ingredients": [ 
       { 
        "id": 1, 
        "label": "Koek" 
       } 
      ], 
      "tags": [], 
      "nutritions": [], 
      "owner": null 
     } 
    ] 
} 

但我要的是量，单位也可以退换！

Answer 1

在序列化嵌套关系时，还必须特别序列化ManyToManyField。

让我给你一个小例子：

class RecipeSerializer(serializers.ModelSerializer): 

    ingredients = serializers.SerializerMethodField() 

    def get_ingredients(self, obj): 
     serializer = IngredientSerializer(obj.ingredients) 
     return serializer.data  

    class Meta: 
     model = Recipe 
     fields = ('id', 'url', 'name', 'ingredients', 'tags', 'nutritions', 'owner') 
     read_only_fields = ('owner',) 
     depth = 1 

无论你的嵌套关系（如成分，标签或营养品），你可以通过创建一个串行方法场序列化。在该方法中，您可以使用特定的序列化程序，以便为您提供所需的json。

请注意方法名称。如果你的ManyToManyField是“成分”，你的方法名应该是“成分”，因为DRF与“get_”一起工作。

欲了解更多信息，检查：

Django Rest Framework - SerializerMethodField

Answer 2

覆盖RecipeSerializer 的方法to_representation和许多的实例传递给很多申请自己的串行器与许多为True。或

标签= serializers.HyperlinkedRelatedField（ 多=真，READ_ONLY =真， ）

Answer 3

我得到了我想要的方式如下：

from recipes.models import Recipe, IngredientTag, Ingredient 
from rest_framework import serializers 

class IngredientTagSerializer(serializers.ModelSerializer): 
    class Meta: 
     model = IngredientTag 
     fields = ('id', 'label') 

class IngredientSerializer(serializers.ModelSerializer): 
    ingredient_tag = IngredientTagSerializer() 

    class Meta: 
     model = Ingredient 
     fields = ('amount', 'unit', 'ingredient_tag') 

class RecipeSerializer(serializers.ModelSerializer): 
    ingredients = IngredientSerializer(source='ingredient_set', many=True) 

    class Meta: 
     model = Recipe 
     fields = ('url', 'name', 'ingredients', 'tags', 'nutritions', 'owner') 
     read_only_fields = ('owner',) 
     depth = 1 

使用作为IngredientSerializer来源的ingredient_tag的ingredient_set产生了我要求的响应：

{ 
    "count": 1, 
    "next": null, 
    "previous": null, 
    "results": [ 
     { 
      "url": "http://localhost:8000/recipes/1/", 
      "name": "Hallo recept", 
      "ingredients": [ 
       { 
        "amount": 200.0, 
        "unit": "g", 
        "ingredient_tag": { 
         "id": 1, 
         "label": "Koek" 
        } 
       }, 
       { 
        "amount": 500.0, 
        "unit": "kg", 
        "ingredient_tag": { 
         "id": 3, 
         "label": "Sugar" 
        } 
       } 
      ], 
      "tags": [], 
      "nutritions": [], 
      "owner": null 
     } 
    ] 
} 

我不知道这是否是最好的方法，所以我会等待直到有人知道他们的DRF留下了评论，或者有人在标记为答案之前发布了更好的东西。