Call multiple ajax and wait for result Angular2 - ajax

Question

I have problem with my Angular. I have this functions:
private callUserInfo(): any {
this.isLoading = true;
return this._ajaxService.getService('/system/ping')
.map(
result => {
this.userId =
result.participant.substring(result.participant.indexOf('#'));
this.isLoading = false;
}
)
.catch(error => {
return Observable.throw(error);
});
}
public loadUserData(userName: string): any {
this.isLoading = true;
return this._ajaxService.getService('/User/' + userName)
.map(
result => {
const data = result[0];
this.user = new User(
data.id,
data.contacts[0].email,
data.name,
data.surname,
data.address.street,
data.address.city,
data.address.state,
data.address.country,
data.address.postCode,
data.address.timeZone);
this.isLoading = false;
})
.catch(error => {
return Observable.throw(error);
});
}
public getUser(): any {
if (this.user == null) {
this.callUserInfo().subscribe(() => {
this.loadUserData(this.userId).subscribe(() => {
return this.user;
});
});
} else {
return this.user;
}
}
In my component I call this service functions like this (auth service is service with functions defined up):
constructor(private _auth: AuthService) {
this.user = _auth.getUser();
}
But it stills return null (because Ajax calls are not finished?) Can someone explain me, how to call this two calls (first is system/ping service and based on return (userId) I need to call second ajax call (/user/id). After this two calls I have defined user in my service and I can return it to other components. Can someone expllain me, what am i doing wrong, or how I can do it better? I´m using newest version of angular.
P.S. Get service is from my wrapper service:
getService(url: string): Observable<any> {
return this.http
.get(this.base + url, this.options)
.map(this.extractData)
.catch(this.handleError);
}

Answer 1

You are not returning anything in case this.user==null
Change your function as following:
userObservabel=new BehaviourSubject(null);
public getUser(): any {
if (this.user == null) {
this.callUserInfo().subscribe(() => {
this.loadUserData(this.userId).subscribe(() => {
this.userObservabel.next(this.user);
});
});
return this.userObservabel.asObservable();
} else {
return this.userObservabel.asObservable();
}
}
and then you need to subscribe it
constructor(private _auth: AuthService) {
_auth.getUser().subscribe(user => this.user = user);
}

Answer 2

You need to call the second service in the subscribe or in the map method i.e. the Observable has returned a promise and that is resolved. Once that is resolved u should call your chained service.
A sample snipped from my POC might help you
this._accountListService.getAccountsFromBE().subscribe(
response => {
this.response = response;
this._accountListService.getAccountSorting().subscribe(
response => {
this.acctSort = response;
if (response.prodCode) {
this._accountListService.getAccountOrder().subscribe(
response => {
this.acctOrder = response;
this.response = this.setAccountOrder(this.response);
this.response.sort(this.myComparator);
this.acctFlag = true;
if (this.prodDesc) {
this.loader = false;
this.accountDetl = this.response[0];
this.accountDetl.entCdeDesc = this.prodDesc[this.accountDetl.entProdCatCde];
}
},
err => console.log(err)
);
}
},
err => console.log(err)
);
},
err => console.log(err)
);