How can you verify if a variable is included in an HTTP response?

Question

How can you verify if a variable is included in an HTTP response?

After successfully creating this authentication service, everything seemed to be running smoothly...

import { HttpClient, HttpHeaders } from '@angular/common/http';
import { tap } from 'rxjs/operators';
import { Storage } from '@ionic/storage';
import { EnvService } from './env.service';
import { Injectable } from '@angular/core';

@Injectable({
  providedIn: 'root'
})

export class AuthService {

  isLoggedIn = false;
  token:any;

  constructor(
    private storage:Storage,
    private http: HttpClient,
    private env: EnvService,
  ) { }

  login(email: String, password: String) {

    let formData = {
      usuario    : email,
      senha      : password,
      retsession : true
    }

    return this.http.post(this.env.API_URL+'/login', formData).pipe(
      tap(response => {
        var token = ('jwt' in response) ? response.jwt : null ;
        this.storage.set('token', token)
        .then(
          () => { console.log('Token Stored: ' + token); },
          error => console.error('Error storing item', error)
        );
        this.token = token;
        this.isLoggedIn = true;
        return token;
      }),
    );
  }

}

Unfortunately, despite its functionality, I encountered a compiling error

[ng] ERROR in src/app/services/auth.service.ts(36,52): error TS2339: Property 'jwt' does not exist on type 'never'.

This issue arises when trying to verify the presence of my token within the HTTP response data...

Can anyone guide me on the correct approach to avoid triggering this error?

angular typescript ionic-framework

Answer 1

Answer №1

In order to verify the existence of the token, you may use the following method:

let token = response['jwt'] ? response['jwt'] : null ;

Warm regards

Answer 2

In order to verify the existence of the token, you may use the following method:

let token = response['jwt'] ? response['jwt'] : null ;

Warm regards

Answer 3

Answer №2

sagat's solution is accurate. Take a look at this example demonstrating how to pass an interface into an http call:

// form-data.interface.ts
export interface FormData {
  username: string;
  password: string;
  rememberSession: boolean;
}

// login-response.interface.ts
export interface LoginResponse {
  token: string;
  // other properties
}

// login.service.ts
login(formData: FormData): Obvservable<LoginResponse> {
  return this.http.post<LoginResponse>(`${this.env.API_URL}/login`, formData);
}

// To implement this in your component (login.component.ts) or state management (login.state.ts)
// use the following code snippet
this.login(formData).subscribe((response) => {
  // handle the response data here
}

Upon sending an http post, you will receive an observable that can be subscribed to. While not necessary in this scenario, pipe and tap achieve similar functionality.

Note: If you anticipate missing values for certain properties in the response, consider using a class instead of an interface:

// login.response.model.ts
export class LoginResponse {
  token: string
  // other properties

  constructor(data: LoginResponse) {
    this.token = (data && data.token) ? data.token : '';
  }
}

This approach guarantees all properties are present on the model, initialized with default values if needed. This helps avoid errors related to missing data fragments.

Answer 4

sagat's solution is accurate. Take a look at this example demonstrating how to pass an interface into an http call:

// form-data.interface.ts
export interface FormData {
  username: string;
  password: string;
  rememberSession: boolean;
}

// login-response.interface.ts
export interface LoginResponse {
  token: string;
  // other properties
}

// login.service.ts
login(formData: FormData): Obvservable<LoginResponse> {
  return this.http.post<LoginResponse>(`${this.env.API_URL}/login`, formData);
}

// To implement this in your component (login.component.ts) or state management (login.state.ts)
// use the following code snippet
this.login(formData).subscribe((response) => {
  // handle the response data here
}

Upon sending an http post, you will receive an observable that can be subscribed to. While not necessary in this scenario, pipe and tap achieve similar functionality.

Note: If you anticipate missing values for certain properties in the response, consider using a class instead of an interface:

// login.response.model.ts
export class LoginResponse {
  token: string
  // other properties

  constructor(data: LoginResponse) {
    this.token = (data && data.token) ? data.token : '';
  }
}

This approach guarantees all properties are present on the model, initialized with default values if needed. This helps avoid errors related to missing data fragments.

How can you verify if a variable is included in an HTTP response?

Answer №1

Answer №2

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