Angular 2 RXJS 可观察

Question

我一定遗漏了一些非常明显的东西......

public suggestedData$: Observable<string[]>;
public suggestionStream = new Subject<string>();

nextSuggestion(){
    this.suggestionStream.next( this.query );
}

this.suggestionStream
    .map(query => {
        return this._someService.getSomeThings( query );
     });

this.suggestionData$ = this.suggestionStream.subscribe();

然后在模板中我想像这样使用 observable：

<ul>
    <li *ngFor="let suggestion of suggestionData$ | async">{{suggestion.something}}</li>
</ul>

Visual Studio 说：Type 'Subscription' is not assignable to type 'Observable<string[]>'. for this.suggestionData$ = this.sug...

有什么想法吗？

编辑：

this.suggestionStream
    .map(query => {
        console.log(query);
            return this._someService.getSomeThings(query);
        })
        .subscribe(res => {
            console.log('res', res);
        });

在控制台中打印：

res Observable {_isScalar: false, source: Observable, operator: MapOperator}

_someService 看起来像这样：

getSomeThings(query: string){

    let params = new URLSearchParams();
    params.set('query', query);

    return this.http.get('https://api.../suggest', {search: params})
        .map(res => res.json() || []);

}

Answer 1

this.suggestionStream.subscribe() 是 Subscription 类型，而不是 Observable。因此，我认为您要实现的目标如下所示：

public suggestedData$: new Observable<string[]>;
public suggestionStream = new Subject<string>();

nextSuggestion(){
  this.suggestionStream.next( this.query );
}

this.suggestionData$ = this.suggestionStream
  .map(query => {
    return this._someService.getSomeValues( query );
  });

异步管道将执行订阅。