Angular2 - How to chain async service calls (http requests) in a component?

Question

I have a component which first need to call a service that POST something. Then in the same component I want to wait until the POST is done, to call another service which

Answer 1

Another way to do the same is to subscribe in the new-version.component.ts and call you GET request from within the POST request i.e check whether your POST request is done Correctly or not if yes POST is done Properly then call you GET request. As below:

In new-version.component.ts:

 private createNewVersion(value) {
    ...
    // create new version, then call on all available versions

    // POST call
    this._newVersionService.createNewVersion(vnr)
        .subscribe((res) => {
            if(res){
                console.log(res);
                if (---Post request done properly check via status or something else here----{
                    CALL YOUR GET REQUEST HERE.....
                    // GET call 
                    this._versionService.getAvailableVersions(); 
                }
                else {
                    DO something else whatever you want....
                }
            }
        });
    ...
}

In new-version.service.ts:

export class NewVersionService {

response$: Subject;

constructor(private _http: Http) {
    this.response$ = new BehaviorSubject(null);
 }

public createNewVersion(versionNr) {    
    this._http.post('http://localhost:8080/nod_inspection_plugin/services/' + versionNr, null, {
        method: 'POST',
    })
    .map(response => {
        return [{status: response.status, json: response.json()}];
    },
    error => console.error(error));
}

for more info related to http request you can read here.