Django Rest框架:如何在验证序列化程序时忽略‘唯一’主键约束？

from rest_framework import serializers

class MyModelSerializer(serializers.ModelSerializer):
    class Meta:
        model = MyModel
        fields = '__all__'

    def validate(self, attrs):
        # 忽略'唯一'主键约束的验证
        if self.instance:
            for field_name, field in self.fields.items():
                if field_name in attrs and field.unique:
                    attrs.pop(field_name)
        return attrs