Django REST Framework - 嵌套序列化程序验证？

Question

所以我有这样的模型:

class Leaderboard(models.Model):
    pass


class Column(models.Model):
    leaderboard = models.ForeignKey(Leaderboard, related_name="columns", on_delete=models.CASCADE)
    related_columns = models.ManyToManyField(self)
    index = models.PositiveIntegerField()

像这样的序列化器:

class ColumnSerializer(ModelSerializer):
    related_columns = serializers.PrimaryKeyRelatedField(queryset=Column.objects.all(), many=True)

    class Meta:
        model = Column
        fields = ('leaderboard', 'related_columns', 'index',)


class LeaderboardSerializer(ModelSerializer):
    children = ColumnSerializer(many=True)

    class Meta:
        model = Leaderboard
        fields = ('columns',)

所以我想做的是验证添加到 related_columns 的任何列为 ColumnSerializer已经属于它的 Leaderboard parent 。在创建 id 期间，我曾多次尝试访问排行榜或排行榜 ID(例如通过在字段中手动指定 ColumnSerializer)。进行验证，但 LeaderboardSerializer 未在 Column 之前初始化，因此我无法验证详细信息。

基本上，我想修改 queryset=Column.objects.all()成为 queryset=self.instance.leaderboard.columns.all()
但是我无权访问 Leaderboard内 Column .例如，如果我访问 self.parent.instance/initial内 ColumnSerializer它是 None直到里面 Leaderboard.validate_columns() .我想到的一件事是只在排行榜方面进行验证，但我仍然认为在 Column 内进行此验证应该是“可行的”。以防我想直接编辑那些，而无需先通过 Leaderboard ...

Answer 1

这是我解决这个问题的方法:

def validate_columns(self, columns):
    if not columns:
        raise serializers.ValidationError("Leaderboards require at least 1 column")

    # Make sure all column indexes are unique
    indexes = [column['index'] for column in columns]
    if len(set(indexes)) != len(columns):
        raise serializers.ValidationError("Columns must have unique indexes!")

    # Make sure all column keys are unique
    keys = [column["key"] for column in columns]
    if len(set(keys)) != len(columns):
        raise serializers.ValidationError("Columns must have unique keys!")

    # Validate that column.computation_indexes points to valid columns
    for column in columns:
        if 'computation_indexes' in column and column['computation_indexes']:
            for index in column['computation_indexes'].split(","):
                try:
                    if int(index) not in indexes:
                        raise serializers.ValidationError(f"Column index {index} does not exist in available indexes {indexes}")
                except ValueError:
                    raise serializers.ValidationError(f"Bad value for index, should be an integer but received: {index}.")

    return columns

我确保这些列是唯一的(在它们的键和索引中)并且它们引用的列也存在。