How can i asynchronouslycall this service function in another component? Angular 11 - node.js

Question

I have an async function getIdentByInfo and in the console i get the right output if i log it in this function. As soon as i call it in another component it doesnt work and i only get 'undefined'. I know it has something to do with beeing ssynchrone and Promises but i cant figure out how to solve my issue. I need the Model class filled with attributes coming from the http request in another component to send them to another service
import { EventEmitter, Injectable } from '#angular/core';
import { HttpClient } from '#angular/common/http';
import { IdentModel } from "../models/identmodel.model";
import { IdentteilComponent } from "../pages/identteil/identteil.component";
#Injectable({
providedIn: 'root',
})
export class InfoWebservice {
url = 'http://localhost:4201';
ident: IdentModel[];
constructor(private http: HttpClient) { }
// promise vom typ IdentModel zurückgeben
getIdentByInfo(id: string, vwk: string) {
this.http.get(this.url).toPromise().then(data => {
for (let i in data){
this.ident.push(data[i])
if ( this.ident[i].identNr == id && this.ident[i].vwk == vwk){
return this.ident[i];
}
}
});
}
}
import { Component, OnInit } from '#angular/core';
import { Router } from '#angular/router';
import { InfoWebservice } from '../../webservices/info.webservice'
import { ImageWebservice } from '../../webservices/image.webservice'
import { IdentModel } from "../../models/identmodel.model";
#Component({
selector: 'app-identteil',
templateUrl: './identteil.component.html',
styleUrls: ['./identteil.component.scss']
})
export class IdentteilComponent implements OnInit {
ident = [];
identNr:string;
vwk:string;
imgFrontLink:string;
imgBackLink:string;
constructor(private router: Router, private service: InfoWebservice, private image: ImageWebservice) { }
getIdentNr() : string {
var split = this.router.url.split("/");
this.identNr = split[2];
return this.identNr;
}
//return type is STRING
getVwk() {
// output von window.location.host = repapp-maw.dbl.de
// var splitHost = window.location.host.split(".");
var splitHost = 'repapp-maw';
var splitV = splitHost.split("-");
this.vwk = splitV[1];
return this.vwk;
}
callInfoService = async () => {
return await this.service.getIdentByInfo(this.getIdentNr(), this.getVwk());
}
ngOnInit() {
console.log(this.callInfoService());
}
}

Answer 1

When you use angular, its always preferred not to use await/Promise. Angular has an in-built RX-JS library which has tonnes of super-awesome functionalities that you can use.
For Example, in your case, you can do something like this:
// Your Service File can make use of 'Behavior Subject'
// Please read more about it here: https://www.learnrxjs.io/learn-rxjs/subjects/behaviorsubject
import { EventEmitter, Injectable } from '#angular/core';
import { HttpClient } from '#angular/common/http';
import { IdentModel } from "../models/identmodel.model";
import { IdentteilComponent } from "../pages/identteil/identteil.component";
#Injectable({
providedIn: 'root',
})
export class InfoWebservice {
url = 'http://localhost:4201';
ident: IdentModel[];
initialIdentValues: IdentModel = [];
private identSource: BehaviorSubject<IdentModel[]> = new BehaviorSubject<IdentModel[]>(this.initialIdentValues);
public identValuesObs$: Observable<IdentModel[]> = this.identSource.asObservable();
// Create a method to set the values in component-1
setIdentValues(identValues: IdentModel[]) {
this.identSource.next(identValues);
}
// Create a method to return values in component-2 or any component
returnIdentValues() {
return this.identValuesObs$;
}
constructor(private http: HttpClient) { }
// Change your service call to this:
getIdentByInfo(id: string, vwk: string): Observable<any> {
return this.http.get(this.url);
}
}
Now in your component-1 where you want to set the values of this identvalues:
// Component-1
constructor(private infoWebService: InfoWebService){}
// Create a method where you get the values
someMethod() {
// Call the API method here and subscribe and then set the values
this.infoWebService.getIdentInfoById(id, vwk).subscribe((data: any) => {
// Your logic goes here ANDD
if (data) {
for (let i in data){
this.ident.push(data[i])
let localIdentsWithRequiredLogic = [];
if ( this.ident[i].identNr == id && this.ident[i].vwk == vwk){
localIdentsWithRequiredLogic.push(this.ident[i]);
}
// THIS IS IMPORTANT
this.infoWebService.setIdentValues(localIdentsWithRequiredLogic);
}
}
})
}
Then in component-2 or whatever component you want, you can retrieve it using the returnIdentValues method like this:
// In component-2
inSomeMethodWhereYouRequireIdentValues() {
this.infoWebService.returnIdentValues().subscribe(data => {
console.log(data) // this is data that you set in component one
})
}