Python 如何在Django REST Framework序列化程序中使用向后关系查找检索多对多字段？

如果标题不正确，请更正。我的问题是我想从

产品

中检索

FinishType

的

名称

。我尝试了两种方法来实现这一点：和。
我在

models.py

中简化了相关模型：

class Product(models.Model):
    product_id = models.CharField(max_length=6)
    color = models.ForeignKey(ColorParent, on_delete=models.SET_NULL, null=True)
    collection = models.ForeignKey(ProductCollection, on_delete=models.SET_NULL, null=True)

    @property
    def get_distributors(self):
        return Distributor.objects.filter(distributor__products=self).count()

    def __str__(self):
        return self.product_id

class FinishType(models.Model):
    name = models.CharField(max_length=50)

    def __str__(self):
        return self.name

class ProductFinishType(models.Model):
    product = models.ForeignKey(Product, on_delete=models.CASCADE)
    market = models.ForeignKey(Market, on_delete=models.CASCADE)
    finish_types = models.ManyToManyField(FinishType)

    def __str__(self):
        return '%s - %s' % (self.product, self.market)

class ProductAlias(models.Model):
    product = models.ForeignKey(Product, on_delete=models.CASCADE)
    market = models.ForeignKey(Market, on_delete=models.CASCADE)
    name = models.CharField(max_length=50, null=True, blank=True)

    def __str__(self):
        return '%s - %s' % (self.product, self.name)

class ProductGridSerializer(serializers.ModelSerializer):
    name = serializers.SerializerMethodField(source='get_name')
    finishing = serializers.SerializerMethodField('get_finish_types')
    distributor = serializers.ReadOnlyField(source='get_distributors')

    @staticmethod
    def get_name(obj):
        return [pa.name for pa in obj.productalias_set.all()]

    @staticmethod
    def get_finish_types(obj):
        return [pft.name for pft in obj.productfinishtype_set.all().select_related('finish_types')]  # first attempt

    class Meta:
        model = Product
        fields = ['id', 'product_id', 'name', 'collection', 'finishing', 'distributor']

My

serializers.py

：

class Product(models.Model):
    product_id = models.CharField(max_length=6)
    color = models.ForeignKey(ColorParent, on_delete=models.SET_NULL, null=True)
    collection = models.ForeignKey(ProductCollection, on_delete=models.SET_NULL, null=True)

    @property
    def get_distributors(self):
        return Distributor.objects.filter(distributor__products=self).count()

    def __str__(self):
        return self.product_id

class FinishType(models.Model):
    name = models.CharField(max_length=50)

    def __str__(self):
        return self.name

class ProductFinishType(models.Model):
    product = models.ForeignKey(Product, on_delete=models.CASCADE)
    market = models.ForeignKey(Market, on_delete=models.CASCADE)
    finish_types = models.ManyToManyField(FinishType)

    def __str__(self):
        return '%s - %s' % (self.product, self.market)

class ProductAlias(models.Model):
    product = models.ForeignKey(Product, on_delete=models.CASCADE)
    market = models.ForeignKey(Market, on_delete=models.CASCADE)
    name = models.CharField(max_length=50, null=True, blank=True)

    def __str__(self):
        return '%s - %s' % (self.product, self.name)

class ProductGridSerializer(serializers.ModelSerializer):
    name = serializers.SerializerMethodField(source='get_name')
    finishing = serializers.SerializerMethodField('get_finish_types')
    distributor = serializers.ReadOnlyField(source='get_distributors')

    @staticmethod
    def get_name(obj):
        return [pa.name for pa in obj.productalias_set.all()]

    @staticmethod
    def get_finish_types(obj):
        return [pft.name for pft in obj.productfinishtype_set.all().select_related('finish_types')]  # first attempt

    class Meta:
        model = Product
        fields = ['id', 'product_id', 'name', 'collection', 'finishing', 'distributor']

第一次尝试适用于

name

字段，该字段获取

ProductAlias

的

name

，但出现以下错误：

/api/product_grids/
select_related:“finish_types”中给出的字段名无效。选择是：产品，市场

我的

get\u finish\u types（）

第二次尝试：

@staticmethod
def get_finish_types(obj):
    product_finish_types = obj.productfinishtype_set.all()
    response = ProductFinishTypeSerializer(product_finish_types, many=True, source='finish_types').data
    return response

它提供了整个对象数据：

{
      "id": 1,
      "product_id": "BQ1111",
      "name": [
            "White Stone"
      ],
      "collection": 1,
      "finishing": [
          {
              "id": 1,
              "product": 1,
              "market": 1,
              "finish_types": [
                  1,
                  3,
                  5
              ]
          }
      ],
      "distributor": 5
},

我想要的输出是这样的：

{
      "id": 1,
      "product_id": "BQ1111",
      "name": [
            "White Stone"
      ],
      "collection": 1,
      "finishing": [
            "Polished",
            "Carved",
            "Melted"
      ],
      "distributor": 5
},

---

为FinishType创建序列化程序

class FinishTypeSerializer(serializers.ModelSerializer):
    class Meta:
        model = FinishType
        fields = ('name',)

并使用SerializerMethodField将其连接到ProductGridSerializer中

class ProductGridSerializer(serializers.ModelSerializer):
    name = serializers.SerializerMethodField(source='get_name')    
    distributor = serializers.ReadOnlyField(source='get_distributors')
    finishing = serializers.SerializerMethodField()

    def get_finishing(self, product):
        qs = FinishType.objects.filter(productfinishtype__product=product)
        return FinishTypeSerializer(qs, many=True).data

    @staticmethod
    def get_name(obj):
        return [pa.name for pa in obj.productalias_set.all()]

    class Meta:
        model = Product
        fields = ['id', 'product_id', 'name', 'collection', 'finishing', 'distributor']

类ProductGridSerializer（serializers.ModelSerializer）：
name=serializers.SerializerMethodField（source='get\u name'）
distributor=serializers.ReadOnlyField（source='get\u distributors'）
finishing=serializers.SerializerMethodField（）
def get_整理（自身、产品）：
qs=FinishType.objects.filter（productfinishtype\uu product=product）
返回FinishTypeSerializer（qs，many=True）
@静力学方法
def get_名称（obj）：
返回[obj.productalias_set.all（）中pa的pa.name]
类元：
型号=产品
字段=['id'、'product\u id'、'name'、'collection'、'finishing'、'distributor']

为

FinishType

创建序列化程序

class FinishTypeSerializer(serializers.ModelSerializer):
    class Meta:
        model = FinishType
        fields = ('name',)

并使用SerializerMethodField将其连接到ProductGridSerializer中

class ProductGridSerializer(serializers.ModelSerializer):
    name = serializers.SerializerMethodField(source='get_name')    
    distributor = serializers.ReadOnlyField(source='get_distributors')
    finishing = serializers.SerializerMethodField()

    def get_finishing(self, product):
        qs = FinishType.objects.filter(productfinishtype__product=product)
        return FinishTypeSerializer(qs, many=True).data

    @staticmethod
    def get_name(obj):
        return [pa.name for pa in obj.productalias_set.all()]

    class Meta:
        model = Product
        fields = ['id', 'product_id', 'name', 'collection', 'finishing', 'distributor']

类ProductGridSerializer（serializers.ModelSerializer）：
name=serializers.SerializerMethodField（source='get\u name'）
distributor=serializers.ReadOnlyField（source='get\u distributors'）
finishing=serializers.SerializerMethodField（）
def get_整理（自身、产品）：
qs=FinishType.objects.filter（productfinishtype\uu product=product）
返回FinishTypeSerializer（qs，many=True）
@静力学方法
def get_名称（obj）：
返回[obj.productalias_set.all（）中pa的pa.name]
类元：
型号=产品
fields=['id'、'product_id'、'name'、'collection'、'finishing'、'distributor']

受@Arakkal Abu的queryset的启发，我第一次尝试了它。

FinishTypeSerializer

添加到

serializers.py

：

class FinishTypeSerializer(serializers.ModelSerializer):
    class Meta:
        model = FinishType
        fields = ('name',)

class ProductGridSerializer(serializers.ModelSerializer):
    name = serializers.SerializerMethodField(source='get_name')
    finishing = serializers.SerializerMethodField(source='get_finishing')
    distributor = serializers.ReadOnlyField(source='get_distributors')

    @staticmethod
    def get_name(obj):
        return [pa.name for pa in obj.productalias_set.all()]

    @staticmethod
    def get_finishing(product):
        return [pft.name for pft in FinishType.objects.filter(productfinishtype__product=product)]

    class Meta:
        model = Product
        fields = ['id', 'product_id', 'name', 'collection', 'finishing', 'distributor']

serializers.py中的
ProductGridSerializer
：

class FinishTypeSerializer(serializers.ModelSerializer):
    class Meta:
        model = FinishType
        fields = ('name',)

class ProductGridSerializer(serializers.ModelSerializer):
    name = serializers.SerializerMethodField(source='get_name')
    finishing = serializers.SerializerMethodField(source='get_finishing')
    distributor = serializers.ReadOnlyField(source='get_distributors')

    @staticmethod
    def get_name(obj):
        return [pa.name for pa in obj.productalias_set.all()]

    @staticmethod
    def get_finishing(product):
        return [pft.name for pft in FinishType.objects.filter(productfinishtype__product=product)]

    class Meta:
        model = Product
        fields = ['id', 'product_id', 'name', 'collection', 'finishing', 'distributor']

JSON输出为：

{
     "id": 1,
     "product_id": "BQ1111",
     "name": [
           "White Stone"
     ],
     "collection": 1,
     "finishing": [
           "Polished",
           "Honed",
           "Carved"
     ],
     "distributor": 5
},

受到@Arakkal Abu的queryset的启发，我第一次尝试了它。

FinishTypeSerializer
添加到
serializers.py
：

class FinishTypeSerializer(serializers.ModelSerializer):
    class Meta:
        model = FinishType
        fields = ('name',)

class ProductGridSerializer(serializers.ModelSerializer):
    name = serializers.SerializerMethodField(source='get_name')
    finishing = serializers.SerializerMethodField(source='get_finishing')
    distributor = serializers.ReadOnlyField(source='get_distributors')

    @staticmethod
    def get_name(obj):
        return [pa.name for pa in obj.productalias_set.all()]

    @staticmethod
    def get_finishing(product):
        return [pft.name for pft in FinishType.objects.filter(productfinishtype__product=product)]

    class Meta:
        model = Product
        fields = ['id', 'product_id', 'name', 'collection', 'finishing', 'distributor']

serializers.py中的
ProductGridSerializer
：

class FinishTypeSerializer(serializers.ModelSerializer):
    class Meta:
        model = FinishType
        fields = ('name',)

class ProductGridSerializer(serializers.ModelSerializer):
    name = serializers.SerializerMethodField(source='get_name')
    finishing = serializers.SerializerMethodField(source='get_finishing')
    distributor = serializers.ReadOnlyField(source='get_distributors')

    @staticmethod
    def get_name(obj):
        return [pa.name for pa in obj.productalias_set.all()]

    @staticmethod
    def get_finishing(product):
        return [pft.name for pft in FinishType.objects.filter(productfinishtype__product=product)]

    class Meta:
        model = Product
        fields = ['id', 'product_id', 'name', 'collection', 'finishing', 'distributor']

JSON输出为：

{
     "id": 1,
     "product_id": "BQ1111",
     "name": [
           "White Stone"
     ],
     "collection": 1,
     "finishing": [
           "Polished",
           "Honed",
           "Carved"
     ],
     "distributor": 5
},

非常感谢。我有很多类似的案例。您的解决方案也非常通用。SerializerMethodField肯定会有帮助。谢谢。我有很多类似的案例。您的解决方案也非常通用。SerializerMethodField确实有帮助。