Angular 2: Convert Observable to Promise

debugcn 投稿 Dev

Dave :

Q) How do I convert the following observable to a promise so I can call it with .then(...)?

My method I want to convert to a promise:

  this._APIService.getAssetTypes().subscribe(
    assettypes => {
        this._LocalStorageService.setAssetTypes(assettypes);
    },
    err => {
        this._LogService.error(JSON.stringify(err))
    },
    () => {}
  );

The service method it calls:

  getAssetTypes() {
    var method = "assettype";
    var url = this.apiBaseUrl + method;

    return this._http.get(url, {})
      .map(res => <AssetType[]>res.json())
      .map((assettypes) => {
        assettypes.forEach((assettypes) => {
          // do anything here you might need....
      });
      return assettypes;
    });      
  }

Thanks!

Günter Zöchbauer :

rxjs6

https://github.com/ReactiveX/rxjs/issues/2868#issuecomment-360633707

Don't pipe. It's on the Observable object by default.
Observable.of('foo').toPromise(); // this

rxjs5

import 'rxjs/add/operator/toPromise';
import 'rxjs/add/operator/map';

...

this._APIService.getAssetTypes()
.map(assettypes => {
  this._LocalStorageService.setAssetTypes(assettypes);
})
.toPromise()
.catch(err => {
  this._LogService.error(JSON.stringify(err));
});

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