GraphQL：字段解析器未在订阅查询中触发？

Posted 2023-03-08

【中文标题】GraphQL：字段解析器未在订阅查询中触发？

【英文标题】：GraphQL: Field Resolver Not Firing on Subscription Query?

【发布时间】：2019-08-16 08:10:07

【问题描述】：

我有一个订阅查询，MessageFolder_Subscription，看起来像这样：

查询

const MESSAGEFOLDER_SUBSCRIPTION_QUERY = gql`
    subscription ($localUserID: String!)
        MessageFolder_Subscription(userID: $localUserID)
            id
            remoteUserData
                id
                name_title
                name_first
                name_last
                [...more fields...]
            
        ,
    
`;

这是它的架构：

架构

type myUserData 
    id: String
    gender: String
    name_title: String
    name_first: String
    *[...more fields...]*


type messageFolder
    id: String
    remoteUserData: myUserData


type Subscription 
    MessageFolder_Subscription(userID: String!): messageFolder

我是这样处理解析器的：

解决者

const resolvers = 
    //FIELD RESOLVER
        MessageFolder_Subscription: 
            subscribe: withFilter(
                () => pubsub.asyncIterator(MSGFOLDER_ADDED_CHANNEL),
                (payload, args) => 
                    debugger; <=== NEVER FIRES

                    if (typeof (payload) === 'undefined') 
                        return false;
                    

                    let result = false;
                    const userId = Meteor.userId();
                     // let messageFolder = MessageFolder_Subscription.messageFolder; 
                    result = (userId === args.fromID || args === MSGFOLDERargs.toID);
                    return result;
                
            )
        ,
    //ROOT RESOLVER
        *[......more resolvers here.....]*
    Subscription: 
        MessageFolder_Subscription: 
            subscribe: withFilter(
                () => pubsub.asyncIterator(MSGFOLDER_ADDED_CHANNEL),
                (payload, args) => 
                    debugger;

                    if (typeof (payload) === 'undefined') 
                        return false;
                    

                    let result = false;
                    const userId = Meteor.userId();
                     // let messageFolder = MessageFolder_Subscription.messageFolder; 
                    result = (userId === args.fromID || args === MSGFOLDERargs.toID);
                    return result;
                
            )
        

当我改变相关项目时，MessageFolder_Subscription 查询会按预期由 pubsub 触发。追溯，我可以看到它返回true。

但由于某种原因，MessageFolder_Subscription 上的字段 remoteUserData 的字段解析器永远不会触发。

我错过了什么？

【参考方案1】：

解决了。我必须添加 __typename: 字段：

const messageFolder_Subscription = 
    __typename: 'messageFolder_Subscription',
    id: userID,

...到MessageFolder_Subscription 订阅对象，当它在突变解析器中创建时，在传递给pubsub 之前。