Trying to loop through object array using ngfor using another header object array to fill a table

Question

I am trying to render an array of objects into a table component inside the collectionsHome Component

CollectionsHomeComponent:

import { Component, OnInit } from '@angular/core';

@Component({
  selector: 'app-collections-home',
  templateUrl: './collections-home.component.html',
  styleUrls: ['./collections-home.component.css']
})
export class CollectionsHomeComponent implements OnInit {

  data = [
    {name: 'James', age: 24, job: 'Designer'},
    {name: 'Jill', age: 26, job: 'Engineer'},
    {name: 'Elyse', age: 25, job: 'Engineer'}
  ];

  headers=[
    {key:'name', label: 'Name'},
    {key:'age', label: 'Age'},
    {key:'job', label: 'Job'}
  ]

  constructor() { }

  ngOnInit(): void {
  }
}

TableComponent

import { Component, OnInit, Input } from '@angular/core';

@Component({
  selector: 'app-table',
  templateUrl: './table.component.html',
  styleUrls: ['./table.component.css']
})
export class TableComponent implements OnInit {

  @Input() data: {name: string; age: number; job: string}[] = [];
  @Input() headers: {key: string; label: string}[] = [];

  constructor() { }

  ngOnInit(): void {
  }

}

CollectionsHomeComponent.html

<app-divider>Table Component</app-divider>
<app-table [data]="data" [headers]="headers"></app-table>

TableComponent.html
I am using ngfor to loop through all the objects in the data array using the key from the headers keys

<table class="ui table">
    <thead>
        <tr>
            <th *ngFor="let header of headers">
                {{header.label}}
            </th>
        </tr>
    </thead>
    <tbody>
        <tr *ngFor="let record of data">
            <td *ngFor="let header of headers">
                {{record[header.key]}}  ---> Throwing Error
            </td>
        </tr>
    </tbody>
</table>

doing this {{record[header.key]}} throws an error and I am not sure why

Here is the error:

Element implicitly has an 'any' type because expression of type 'string' can't be used to index type '{ name: string; age: number; job: string; }'.
 No index signature with a parameter of type 'string' was found on type '{ name: string; age: number; job: string; }'.ngtsc(7053)
table.component.ts(4, 40): Error occurs in the template of component TableComponent.

The only way to get this working is if I change the input types to any like this

import { Component, OnInit, Input } from '@angular/core';

@Component({
  selector: 'app-table',
  templateUrl: './table.component.html',
  styleUrls: ['./table.component.css']
})
export class TableComponent implements OnInit {

  @Input() data: any = [];
  @Input() headers: any = [];

  constructor() { }

  ngOnInit(): void {
  }

}

Can someone help me understand why? I feel like using any in cases like this is not best practices

Answer 1

define the table header and data type like

export interface TableDataType {
  name: string;
  age: number;
  job: string;
}

export interface TableHeader {
  key: string;
  label: string;
}

and use in table component

@Component({
  selector: 'app-table',
  templateUrl: './table.component.html',
})
export class TableComponent implements OnInit {
  @Input() data: Array<TableDataType>[];
  @Input() headers: Array<TableHeader> = [];

  constructor() {}

  ngOnInit(): void {}
}

here is the live working code https://stackblitz.com/edit/angular-2khgqx?file=src/app/table-demo/table.component.ts