javascript - Error trying to diff '[object Object]'. Only arrays and iterables are allowed in Angular-11 Applica

with *ngFor, I cannot fetch the data from my ponent.ts to my ponent.html

The same method works for one class but does not work for another class.

Here is my service class

export class FoodListService {
  private url = environment.serverURL;

  constructor(private http: HttpClient) {
  }

  //get all products from one store
  getAllProducts(storeId: Number): Observable<FoodListModelServer[]> {
    return this.http.get<FoodListModelServer[]>(this.url + 'foodlist/' + storeId);
  }

Here is my ponent class

export class FoodListComponent implements OnInit {

  foodlist: FoodListModelServer[] = [];
  
constructor(private foodListService: FoodListService, private router: Router, private route: ActivatedRoute) {}

ngOnInit(): void {
    
      this.foodListService.getAllProducts(this.storeId).subscribe(food => {

        this.foodlist = food;
        console.log(this.foodlist);
      });    
   }
}

Here is my ponent.html

<div class="col-md-8 col-lg-10 col-sm-6 card">
        <li *ngFor="let foodlist of foodlist">
            {{foodlist.food_name}}
            
        </li>
</div>

Console.log(this.foodlist)

I get and object {count: 5, stores: Array(5)}

Why do I get a count included forming an object instead of just the Array?

How do I get only the array?

I have same code with the other ponent and it works fine. I tried everything mentioned online with no progress.

with *ngFor, I cannot fetch the data from my ponent.ts to my ponent.html

The same method works for one class but does not work for another class.

Here is my service class

export class FoodListService {
  private url = environment.serverURL;

  constructor(private http: HttpClient) {
  }

  //get all products from one store
  getAllProducts(storeId: Number): Observable<FoodListModelServer[]> {
    return this.http.get<FoodListModelServer[]>(this.url + 'foodlist/' + storeId);
  }

Here is my ponent class

export class FoodListComponent implements OnInit {

  foodlist: FoodListModelServer[] = [];
  
constructor(private foodListService: FoodListService, private router: Router, private route: ActivatedRoute) {}

ngOnInit(): void {
    
      this.foodListService.getAllProducts(this.storeId).subscribe(food => {

        this.foodlist = food;
        console.log(this.foodlist);
      });    
   }
}

Here is my ponent.html

<div class="col-md-8 col-lg-10 col-sm-6 card">
        <li *ngFor="let foodlist of foodlist">
            {{foodlist.food_name}}
            
        </li>
</div>

Console.log(this.foodlist)

I get and object {count: 5, stores: Array(5)}

Why do I get a count included forming an object instead of just the Array?

How do I get only the array?

I have same code with the other ponent and it works fine. I tried everything mentioned online with no progress.

• javascript
• angular
• typescript
• rxjs
• angular-ui-router

Share Improve this question Follow asked Sep 29, 2021 at 10:21 glimzglimz 3311 gold badge11 silver badge55 bronze badges

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2 Answers 2

Sorted by: Reset to default 1

Why do I get a count included forming an object instead of just the Array?

• it depends on the implementation of API on the backend side

How do I get only the array?

1. create interface for the actual response from API and use here this.http.get<FoodListModelServerResponse>
2. then we can extract value from response via RxJs map operator - map(response => response.stores) (find more info here: https://www.learnrxjs.io/learn-rxjs/operators/transformation/map)
3. that is it, you can subscribe to getAllProducts and you will get the array

import { map } from 'rxjs/operators';

export interface FoodListModelServerResponse {
count: number;
stores: FoodListModelServer[];
}

export class FoodListService {
  private url = environment.serverURL;

  constructor(private http: HttpClient) {
  }

  getAllProducts(storeId: Number): Observable<FoodListModelServer[]> {
    return this.http.get<FoodListModelServerResponse >(this.url + 'foodlist/' + storeId)
.pipe(map(response => response.stores));
  }

then you can use your implementation

ngOnInit(): void {
    
      this.foodListService.getAllProducts(this.storeId).subscribe(food => {

        this.foodlist = food;
        console.log(this.foodlist);
      });    
   }
}

Use RxJs pluck operator to extract stores out of response object. Declare foodlist variable as foodlist$: Observable<FoodListModelServer[]> so that it is assignable to observable.

In foodService return Observable<any> like getAllProducts(storeId: Number): Observable<any>

import { pluck} from 'rxjs/operators';
import { Observable } from 'rxjs';

export class FoodListComponent implements OnInit {

    foodlist$: Observable<FoodListModelServer[]>;
      
    constructor(private foodListService: FoodListService, private router: Router, private route: ActivatedRoute) {}

    ngOnInit(): void {
          this.foodlist$ = this.foodListService.getAllProducts(this.storeId).pipe(
            pluck('stores')
          ); 
     }
}

In template use Async pipe, it will take care of subscribing and unsubscribing to your foodListService.getAllProducts

<div class="col-md-8 col-lg-10 col-sm-6 card">
    <li *ngFor="let foodlist of foodlist$ | async">
        {{foodlist.food_name}}
    </li>
</div>