运行测试遇TypeError：QuestionnaireType无connection，如何解决？

原因 #

使用DjangoFilterConnectionField要求对应的GraphQL类型（此处为QuestionnaireType）必须关联有效的Connection类型。如果QuestionnaireType只是普通的DjangoObjectType，未配置Relay Node接口或生成对应的Connection类，就会触发该错误。

解决方法 #

方法一：自动生成Connection（推荐） #

定义QuestionnaireType时，继承DjangoObjectType并指定graphene.relay.Node接口，框架会自动生成对应的Connection类型：

import graphene
from graphene_django import DjangoObjectType
from graphene_django.filter import DjangoFilterConnectionField
from .models import Questionnaire

class QuestionnaireType(DjangoObjectType):
    class Meta:
        model = Questionnaire
        # 启用Relay Node接口，自动生成Connection
        interfaces = (graphene.relay.Node,)
        # 可选：配置允许过滤的字段
        filter_fields = {
            'title': ['exact', 'icontains'],
            'created_at': ['gte', 'lte'],
        }

class Query(graphene.ObjectType):
    all_questionnaires = DjangoFilterConnectionField(QuestionnaireType)

方法二：手动定义自定义Connection #

如果需要给Connection添加自定义字段，可以手动创建Connection类并关联：

import graphene
from graphene import relay
from graphene_django import DjangoObjectType
from graphene_django.filter import DjangoFilterConnectionField
from .models import Questionnaire

class QuestionnaireType(DjangoObjectType):
    class Meta:
        model = Questionnaire
        interfaces = (graphene.relay.Node,)

# 自定义Connection类
class QuestionnaireConnection(relay.Connection):
    # 可添加自定义字段，比如total_count
    total_count = graphene.Int()

    def resolve_total_count(self, info):
        return self.iterable.count()

    class Meta:
        node = QuestionnaireType

class Query(graphene.ObjectType):
    all_questionnaires = DjangoFilterConnectionField(QuestionnaireConnection)

内容的提问来源于stack exchange，提问作者Rodrigo