具有多对多关系的DRF 2路嵌套序列化

Question

我使用中间模型在我的[[学生和宏模型之间具有多对多关系

class Person(models.Model):
    # cf/NIN optional by design
    cf = models.CharField(_('NIN'), unique=True, blank=True, null=True, max_length=16)
    first_name = models.CharField(_('first name'), blank=False, max_length=40)
    last_name = models.CharField(_('last name'), blank=False, max_length=40)
    date_of_birth = models.DateField(_('date of birth'), blank=False)

    class Meta:
        ordering = ['last_name', 'first_name']
        abstract = True

    def __str__(self):
        return self.first_name + ' ' + self.last_name


class Macro(models.Model):
    name = models.CharField(_('name'), unique=True, blank=False, max_length=100)
    description = models.TextField(_('description'), blank=True, null=True)

    class Meta:
        ordering = ['name']

    def __str__(self):
        return self.name


class Student(Person):
    enrollment_date = models.DateField(_('enrollment date'), blank=True, null=True)
    description = models.TextField(_('description'), blank=True, null=True)
    macro = models.ManyToManyField(Macro, through='MacroAssignement')


class MacroAssignement(models.Model):
    student = models.ForeignKey(Student, related_name='macros', on_delete=models.CASCADE)
    macro = models.ForeignKey(Macro, related_name='students', on_delete=models.CASCADE)

    def __str__(self):
        return str(self.student)

我配置序列化程序以便在对学生进行序列化时利用嵌套序列化
class PersonSerializer(serializers.ModelSerializer):
    class Meta:
        model = Person
        fields = ('id',
                  'cf',
                  'first_name',
                  'last_name',
                  'date_of_birth')
        abstract = True


class StudentSerializer(PersonSerializer):
    macro = serializers.StringRelatedField(many=True, read_only=True)

    class Meta(PersonSerializer.Meta):
        model = Student
        fields = PersonSerializer.Meta.fields + ('enrollment_date',
                                                 'description',
                                                 'macro')
        extra_kwargs = {'enrollment_date': {'default': date.today()},
                        'description': {'required': False}}


class MacroSerializer(serializers.ModelSerializer):
    students = StudentSerializer(many=True, read_only=True)

    class Meta:
        model = Macro
        fields = ('id',
                  'name',
                  'description',
                  'students')

直到这里，没有问题，当我请求
student

数据时，macro相关信息随之出现。这是一个例子

    {
        "id": 18,
        "cf": "ciaciacia",
        "first_name": "Paolo",
        "last_name": "Bianchi",
        "date_of_birth": "2020-05-01",
        "enrollment_date": null,
        "description": null,
        "macro": [
            "macro1"
        ]
    },

现在相反，当我请求
宏]时，我也想查看相关的学生列表。我也尝试在MacroSerializer中实现嵌套序列化class MacroSerializer(serializers.ModelSerializer):
        students = StudentSerializer(many=True, read_only=True)
这不起作用，因为出现以下错误
AttributeError: Got AttributeError when attempting to get a value for field `first_name` on serializer `StudentSerializer`.
The serializer field might be named incorrectly and not match any attribute or key on the `MacroAssignement` instance.
Original exception text was: 'MacroAssignement' object has no attribute 'first_name'.
[注意：first_name是从[[Person
模型继承的
Student模型的字段]当然，我可以实现查询数据库并获取分配给给定宏的学生姓名的功能，但是我想知道是否有内置的Django方法。有点像[[2-way嵌套序列化

我使用中间模型类Person（models.Model）在我的Student模型和Macro模型之间具有多对多关系：＃cf / NIN设计为可选cf = models.CharField（_（'NIN'）， ...

Answer 1