recuperate fields of a json - json

Question

I have a json like this :
[ {
"id": 1,
"libraryName": "lib1",
"bookName": "book1",
"bookPrice": 250.45,
"unitSold": 305
},
{
"id": 2,
"libraryName": "lib1",
"bookName": "book2",
"bookPrice": 450.45,
"unitSold": 150
},
{
"id": 3,
"libraryName": "lib1",
"bookName": "book3",
"bookPrice": 120.25,
"unitSold": 400
}]
I want to recuperate all the bookNames of this json in a list without creating the method getBookNames (because I want a standard way for any field of the json)
So, in the component.ts I used :
sales:any;
getSale () {
this.service.getSales().subscribe(data=> {this.sales = data,
console.log(this.sales.bookName)
})
}
It gives me undefined object in the console ! How can I solve this without creating a method getBookNames() ?
This is my class :
export interface Sale {
id: number
bookname : string
Libraryname: string
Bookprice : number
Unitsold : number
}
This is my service:
import { Injectable } from '#angular/core';
import { HttpClient } from '#angular/common/http';
import { Sale } from './Sale';
#Injectable({
providedIn: 'root'
})
export class MyserviceService {
constructor(private http: HttpClient) { }
getSales () {
return this.http.get<Sale>("http://localhost:8081/sales/all")
}
}

Answer 1

The data obtained from the API is an array. So you could use array map() function to obtain a list of all the properties from the elements. Try the following
sales: any;
unitsSold = [];
getSale () {
this.service.getSales().subscribe(data=> {
this.sales = data,
console.log(data.map(item => item.bookName)); // <-- output: ['book1', 'book2', 'book3'];
console.log(data.map(item => item.id)); // <-- output: [1, 2, 3];
this.unitsSold = data.map(item => item.unitSold); // <-- [305, 150, 400]
});
}
I don't see anything lost here to recuperate.