javascript - RxJS5 与延迟可观察值结合的高级示例

Question

嘿，我遇到了 RxJS 组合运算符的问题...

这是示例对象:

const userData = {
        dbKeyPath: 'www.example.com/getDbKey',
        users:[
            {name:'name1'},
            {name:'name2'},
            {name:'name3'}
        ]
    }

使它们变得可观察:

const userDataStream  = Rx.Observable.of(userData)
const dbKeyStream : string = this.userDataStream.mergeMap(_userData => getDbKey(_userData.dbKeyPath))
const userStream = this.userDataStream.pluck('users').mergeMap(_users=>Rx.Observable.from(_users))

我的预期结果是具有组合可观察量的流:

[user[0],dbKey],[user[1],dbKey],[user[2],dbKey]... 

它与 withLatestFrom 运算符配合得很好:

const result = userStream.withLatestFrom(dbKeyStream) // [user, dbkey]

但是，当我将 .delay() 运算符应用于 dbKeyStream 时，如何归档相同的结果？

Answer 1

我建议使用mergeMap overload with the selectorFunc :

const userData = {
        dbKeyPath: 'www.example.com/getDbKey',
        users:[
            {name:'name1'},
            {name:'name2'},
            {name:'name3'}
        ]
    };

function getDbKey(path) {
  return Rx.Observable.of('the-db-key:'+path)
    .do(() => console.log('fetching db key for path: '+ path))
    .delay(1000);
}

const userDataStream  = Rx.Observable.of(userData)
  .mergeMap(
    _userData => getDbKey(_userData.dbKeyPath),
    (_userData, dbKey) => _userData.users.map(_usr => ({ user: _usr, dbKey }))
  )
.subscribe(console.log);

<script src="https://cdnjs.cloudflare.com/ajax/libs/rxjs/5.0.3/Rx.js"></script>

这将为您提供输入对象和每个输出值，以便根据需要组合在一起。