Nested foreign key в djangorestframework

Вот код

    class Meta:
        model = Task
        fields = ('id', 'column', 'title', 'description')

class TaskColumnTreeSerializer(serializers.ModelSerializer):
    tasks = TaskTreeSerializer(many=True)

    class Meta:
        model = TaskColumn
        fields = ('id', 'board', 'name', 'tasks')

class BoardTreeSerializer(serializers.ModelSerializer):
    columns = TaskColumnTreeSerializer(many=True)

    class Meta:
        model = Board
        fields = ('id', 'name', 'description', 'columns')

Вот такую ошибку выдает

Got AttributeError when attempting to get a value for field `columns` on serializer `BoardTreeSerializer`.
The serializer field might be named incorrectly and not match any attribute or key on the `Board` instance.
Original exception text was: 'Board' object has no attribute 'columns'.

Что делать?