Get array inside JSON API response

Question

I'm trying to make an application with both front-end and back-end. I have finished both, but now I'm having some trouble trying to connect them. I keep getting this error:

catalog.component.ts:45 ERROR Error: NG0900: Error trying to diff '[object Object]'. Only arrays and iterables are allowed at DefaultIterableDiffer.diff (core.mjs:28514:19)

First, I'm trying to get the array response, where the products are located:

product.service.ts

public getAll(): Observable<Product[]> {
  return this.http.get<Response["response"]>(this.productsUrl);
}

This method receives the following response:

{
    "httpCode": 200,
    "message": "OK",
    "response": [
        {
            "pieceName": "Mini Figure Trophy",
            "pieceImageURL": "https://www.lego.com/cdn/product-assets/element.img.lod5photo.192x192/6335932.jpg",
            "piecePrice": 0.3,
            "pieceTag": "Bestseller",
        },
        {
            "pieceName": "Animal No. 17 Dog",
            "pieceImageURL": "https://www.lego.com/cdn/product-assets/element.img.lod5photo.192x192/6076467.jpg",
            "piecePrice": 2.76,
            "pieceTag": "Bestseller",
        }
    ]
}

Then, when my catalog page opens, I run these two functions:

catalog.component.ts

ngOnInit(): void {
  this.getProducts();
    
  this.searchSubject.subscribe(value => this.searchService.setSearchValue(value));

  this.searchService.searchValue$.subscribe(value => {
    this.productService.getProductByNameLike(value).subscribe(productsCalled => {
      this.products = productsCalled})
  })
}

getProducts(): void {
  this.productService.getAll().subscribe({ <- Line where the error occurs
    next: (productsCalled: Product[]) => {
      this.products = productsCalled
      this.checkProductsOnCart()
    },
    error: (err) => console.log(err),
    complete: () => console.log("completo")
  });
}

But I keep getting the NG0900 error. I believe it might be because I'm not reading the array where the products are.

I have changed the getAll method, as originally it was:

public getAll(): Observable<Product[]> {
  return this.http.get<Product[]>(this.productsUrl);
}

I also tried searching for other responses here, but none seem to be applicable to my problem, or maybe I'm just too much of a newbie to see the relation. Does anyone know what am I doing wrong here? Thanks in advance.

Yong Shun · Accepted Answer · 2022-12-19 14:06:46Z

1

Your JSON response is an object.

export interface ProductListResponse {
  httpCode: Number;
  message: string;
  response: Product[];
}

Work with map from rxjs to return the array from the response property.

import { map } from 'rxjs';

public getAll(): Observable<Product[]> {
  return this.http.get<ProductListResponse>(this.productsUrl)
    .pipe(map((data) => data.response));
}

answered Dec 19, 2022 at 14:06

Yong Shun

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