Manage both the return of an observable and the setting of a value within a single method using

Question

Manage both the return of an observable and the setting of a value within a single method using

I am in need of a service that can both return an observable and set a value to a field within the same method.

The current implementation of my userService.getUserDetails() method is as follows:

private requestUrl: string;
private bic: string;
private id: string;
private name: string;

getUserDetails(): Observable<User> {
this.bic = 'aaa';
this.id= '123';

this.requestUrl = `${configs.api}v1/bics/` + encodeURIComponent(this.bic) + `/ids/` + encodeURIComponent(this.id) + `/users`;

const userObservable = this.http.get<User>(this.requestUrl).pipe(catchError(this.handleError));

userObservable.subscribe(data => this.name = data.name);

return userObservable;
}

When calling getUserDetails, I aim to achieve two objectives: 1) Return Observable<User> 2) Set the name value for later access in other classes by injecting this service without re-triggering the http request. This is what I envision:

  getName() {
return this.name;
 }

However, I am uncertain about using subscribe because I encounter undefined values when attempting to use the stored value. What would be the most appropriate approach to tackle this issue?

angular typescript http

Answer 1

Answer №1

Here is an example of how to utilize the observable:

   public name: string;
   public bic: string;
   public id: string;

   public getUserDetails(): Observable<User> {
        this.bic = '...';
        this.id = '...';
        this.requestUrl = `${configs.api}v1/bics/` + encodeURIComponent(this.bic) + `/ids/` + encodeURIComponent(this.id) + `/users`;

        return this.http.get<User>(this.requestUrl).pipe(catchError(this.handleError));
    }

It's best practice for this method to be in a service, solely responsible for returning the observable and handling errors.

In your component, you can implement it like so:

    constructor(private readonly _yourService: YourService) {}

    public ngOnInit(): void {
    this.getUserDetails();
    console.log(this._yourService.name) // may output undefined as the observable execution is asynchronous
    }

    public getUserDetails(): void{
    this._yourService.getUserDetails().subscribe(
    data => {
    this._yourService.name = data.name;
    // continue with other operations as now this.name should hold the expected value.
    }
    )
    }

Alternatively, you have the option to handle all these tasks within the service itself. Ultimately, the decision lies with your design preferences.

Answer 2

Here is an example of how to utilize the observable:

   public name: string;
   public bic: string;
   public id: string;

   public getUserDetails(): Observable<User> {
        this.bic = '...';
        this.id = '...';
        this.requestUrl = `${configs.api}v1/bics/` + encodeURIComponent(this.bic) + `/ids/` + encodeURIComponent(this.id) + `/users`;

        return this.http.get<User>(this.requestUrl).pipe(catchError(this.handleError));
    }

It's best practice for this method to be in a service, solely responsible for returning the observable and handling errors.

In your component, you can implement it like so:

    constructor(private readonly _yourService: YourService) {}

    public ngOnInit(): void {
    this.getUserDetails();
    console.log(this._yourService.name) // may output undefined as the observable execution is asynchronous
    }

    public getUserDetails(): void{
    this._yourService.getUserDetails().subscribe(
    data => {
    this._yourService.name = data.name;
    // continue with other operations as now this.name should hold the expected value.
    }
    )
    }

Alternatively, you have the option to handle all these tasks within the service itself. Ultimately, the decision lies with your design preferences.

Answer 3

Answer №2

Implement the use of "tap" in your service

name:any;
const userObservable = this.http.get<User>(this.requestUrl).pipe(
tap((res)=>{
    this.name=res;
}),
catchError(this.handleError)
);

Occasionally, a form of "cache" is utilized

name:any;
const userObservable = (this.name)?of(name):
  this.http.get<User>(this.requestUrl).pipe(
    tap((res)=>{
      this.name=res;
    }),
      catchError(this.handleError)
    );

You have the ability to subscribe to the function at any time. The initial call triggers an HTTP request, while subsequent calls utilize the value stored in "name" - of(name) returns an observable.

Answer 4

Implement the use of "tap" in your service

name:any;
const userObservable = this.http.get<User>(this.requestUrl).pipe(
tap((res)=>{
    this.name=res;
}),
catchError(this.handleError)
);

Occasionally, a form of "cache" is utilized

name:any;
const userObservable = (this.name)?of(name):
  this.http.get<User>(this.requestUrl).pipe(
    tap((res)=>{
      this.name=res;
    }),
      catchError(this.handleError)
    );

You have the ability to subscribe to the function at any time. The initial call triggers an HTTP request, while subsequent calls utilize the value stored in "name" - of(name) returns an observable.

Manage both the return of an observable and the setting of a value within a single method using

Answer №1

Answer №2

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