When iterating through a loop, I encounter difficulties accessing array values, yet the values are visible when written to the console

Question

When iterating through a loop, I encounter difficulties accessing array values, yet the values are visible when written to the console

Currently, I am facing a peculiar issue where I retrieve the user's profile from Firebase, and within this profile lies a Photo Object containing an array of photos uploaded by the user.

This is my getUserProfile method:

getUserProfile(): Observable<User> {

    var userId = null;

    var auth = this.af.auth.subscribe(user => {
        userId = user.uid;
    });

    auth.unsubscribe();

    return this.af.database.object('/users/' + userId)
        .map(pro => new User(
            pro.$key,
            pro['email'],
            pro['gender'],
            pro['last_name'],
            pro['first_name'],
            pro['display_name'],
            pro['photos'],
            pro['hobbies']))
}

The structure of my User class is as follows:

export class User {
    public constructor(
        public userId: string,
        public email: string,
        public gender?: string,
        public last_name?: string,
        public first_name?: string,
        public display_name?: string,
        public photos: Photo[] = [],
        public hobbies: Hobbies[] = [],
    ) { }
}

In my component, I invoke the getUserProfile method like this:

this.userSubscription = this.profileService.getUserProfile().subscribe(profile => {
   console.log(profile.photo);
});

Despite logging console.log(profile.photos);, when attempting to loop through the collection with:

for(var i = 0; i < profile.photos.length; i++){
   console.log('here');
}

No output is displayed in the console. Even trying

console.log(profile.photos.length);

results in 'undefined'.....

I am not entirely certain what could be causing this issue. Can anyone identify why looping through the photo array and accessing its properties seems to be failing?

angular typescript

Answer 1

Answer №1

When working with the profile.photos object, it's important to note that it is not an array but rather an object. To effectively handle this in your interface, update the photos member to:

public photos: {[index: string]: Photo} = {}

To iterate through this object, you can use the following code snippet:

for(let key in profile.photos) { 
    let photo = profile.photos[key];
    //... 
}

UPDATE

If you're looking for other methods to retrieve all property values from a JavaScript Object without knowing the keys, check out this resource: How to get all properties values of a Javascript Object (without knowing the keys)?

Answer 2

When working with the profile.photos object, it's important to note that it is not an array but rather an object. To effectively handle this in your interface, update the photos member to:

public photos: {[index: string]: Photo} = {}

To iterate through this object, you can use the following code snippet:

for(let key in profile.photos) { 
    let photo = profile.photos[key];
    //... 
}

UPDATE

If you're looking for other methods to retrieve all property values from a JavaScript Object without knowing the keys, check out this resource: How to get all properties values of a Javascript Object (without knowing the keys)?

Answer 3

Answer №2

If your code is being broken by syntax issues, consider trying the following solution:

const subscription = this.profileService.getUserProfile().subscribe(profile => {
  console.log(profile.photo);
  for (const entry of profile.photo) {
    console.log(entry); 
  }
});

For more information, you can refer to: https://www.typescriptlang.org/docs/handbook/iterators-and-generators.html

Answer 4

If your code is being broken by syntax issues, consider trying the following solution:

const subscription = this.profileService.getUserProfile().subscribe(profile => {
  console.log(profile.photo);
  for (const entry of profile.photo) {
    console.log(entry); 
  }
});

For more information, you can refer to: https://www.typescriptlang.org/docs/handbook/iterators-and-generators.html

Answer 5

Answer №3

Give this a shot, it's as simple as this

service.ts

import 'rxjs/add/operator/mergeMap';

import {User} from './user';

export default class Service {
  getUserProfile(): Observable<User> {
    return this.af.auth.flatMap(({ id }) =>
      this.af.database.object('/users/' + id)
    );
  }
}

component.ts

import Service from './service';

export class Component {
  constructor(readonly service: Service) { }

  ngOnInit() {
    this.service.getUserProfile().subscribe(({ photos = [] }) => {
      photos.forEach(console.log);
    });
  }
}

user.ts

export interface User {
  userId: string,
  email: string,
  gender?: string,
  last_name?: string,
  first_name?: string,
  display_name?: string,
  photos: Photo[],
  hobbies: Hobbies[];
}

No need to manually deserialize and pack values into a User class, just utilize an interface. No mutable security variables. No concerns about subscriptions, at least for now. Focus on solving the main issue at hand.

Answer 6

Give this a shot, it's as simple as this

service.ts

import 'rxjs/add/operator/mergeMap';

import {User} from './user';

export default class Service {
  getUserProfile(): Observable<User> {
    return this.af.auth.flatMap(({ id }) =>
      this.af.database.object('/users/' + id)
    );
  }
}

component.ts

import Service from './service';

export class Component {
  constructor(readonly service: Service) { }

  ngOnInit() {
    this.service.getUserProfile().subscribe(({ photos = [] }) => {
      photos.forEach(console.log);
    });
  }
}

user.ts

export interface User {
  userId: string,
  email: string,
  gender?: string,
  last_name?: string,
  first_name?: string,
  display_name?: string,
  photos: Photo[],
  hobbies: Hobbies[];
}

No need to manually deserialize and pack values into a User class, just utilize an interface. No mutable security variables. No concerns about subscriptions, at least for now. Focus on solving the main issue at hand.

When iterating through a loop, I encounter difficulties accessing array values, yet the values are visible when written to the console

Answer №1

Answer №2

Answer №3

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