Angular2搜索将布尔值添加到地图valueChanges

Question

this.searchField.valueChanges
      .debounceTime(400)
      .distinctUntilChanged()
      .switchMap(term => this.data(term), this.variable = true)
      .subscribe((result) => {
        this.variable = false;

      });

In the above code i want to make the this.variable to true when the this.data observable method is being called. This is the way i tried but it gives error that it's not a observable method

Answer 1

I don't know what you wanted to do with switchMap but if you want to initialize an Observable chain you can use startWith() operator.

this.searchField.valueChanges
    .debounceTime(400)
    .startWith(true)

Or if you want to always pass only true value you can use mapTo :

this.searchField.valueChanges
    .debounceTime(400)
    .mapTo(true)

Answer 2

Use do operator

Perform a side effect for every emission on the source Observable, but return an Observable that is identical to the source.

http://reactivex.io/rxjs/class/es6/Observable.js~Observable.html#instance-method-do

 this.searchField.valueChanges
  .debounceTime(400)
  .distinctUntilChanged()
  .switchMap(term => this.data(term))
  .do(x => this.variable = true)
  .subscribe((result) => {
    this.variable = false;

  });