如何使用Django Rest框架中的中间表来序列化自递归多对多模型？

from django.db import models

class Category(models.Model):
    name = models.CharField(max_length=100)
    parent = models.ManyToManyField('self', blank=True, symmetrical=False, through='CategoryRelation')

    def __str__(self):
        return self.name

class CategoryRelation(models.Model):
    from_category = models.ForeignKey(Category, related_name='relations', on_delete=models.CASCADE)
    to_category = models.ForeignKey(Category, related_name='reverse_relations', on_delete=models.CASCADE)
    is_primary = models.BooleanField(default=False)

    def __str__(self):
        return f'{self.from_category} -> {self.to_category}'

from rest_framework import serializers

class CategorySerializer(serializers.ModelSerializer):
    relations = serializers.SerializerMethodField()

    def get_relations(self, instance):
        relations = instance.relations.filter(is_primary=True)
        return CategoryRelationSerializer(relations, many=True).data

    class Meta:
        model = Category
        fields = '__all__'

class CategoryRelationSerializer(serializers.ModelSerializer):
    class Meta:
        model = CategoryRelation
        fields = '__all__'