Unable to get check box to show on data table in Angular

I am trying to combine the 'Table With Expandable Rows' with the 'Table with Selection' because I want to use the mat-checkbox with the expandable row from the angular material site (https://material.angular.dev/components/table/examples). I am unable to get a mat-checkbox to show on a data table.

html

<table
mat-table
[dataSource]="dataSource"
multiTemplateDataRows
class="mat-elevation-z8"
>
<ng-container
matColumnDef="{{column}}"
*ngFor="let column of columnsToDisplay"
>
<ng-container *ngIf="column !== 'action'; else action">
<th mat-header-cell *matHeaderCellDef>{{column}}</th>
<td mat-cell *matCellDef="let element">{{element[column]}}</td>
</ng-container>
<ng-template #action>
<th mat-header-cell *matHeaderCellDef>Actions</th>
<td mat-cell *matCellDef="let element" class="checkbox-spacing">
<mat-icon
(click)="expandedElement = expandedElement === element ? null : element"
>{{expandedElement === element ? 'expand_less' :
'expand_more'}}</mat-icon
>
<!-- <input type="checkbox" /> -->
</td>
<!-- <mat-checkbox></mat-checkbox> -->
</ng-template>
</ng-container>
<ng-container matColumnDef="select">
<th mat-header-cell *matHeaderCellDef>
<mat-checkbox
(change)="$event ? toggleAllRows() : null"
[checked]="selection.hasValue() && isAllSelected()"
[indeterminate]="selection.hasValue() && !isAllSelected()"
[aria-label]="checkboxLabel()"
>
</mat-checkbox>
</th>
<td mat-cell *matCellDef="let row">
<mat-checkbox
(click)="$event.stopPropagation()"
(change)="$event ? selection.toggle(row) : null"
[checked]="selection.isSelected(row)"
[aria-label]="checkboxLabel(row)"
>
</mat-checkbox>
</td>
</ng-container>

<!-- Expanded Content Column - The detail row is made up of this one column that spans across all columns -->
<ng-container matColumnDef="expandedDetail">
<td
mat-cell
*matCellDef="let element"
[attr.colspan]="columnsToDisplay.length"
>
<div
class="example-element-detail"
[@detailExpand]="element == expandedElement ? 'expanded' : 'collapsed'"
>
<div class="example-element-diagram">
<div class="example-element-position">{{element.position}}</div>
<div class="example-element-symbol">{{element.symbol}}</div>
<div class="example-element-name">{{element.name}}</div>
<div class="example-element-weight">{{element.weight}}</div>
</div>
<div class="example-element-description">
{{element.description}}
<span class="example-element-description-attribution">
-- Wikipedia
</span>
</div>
</div>
</td>
</ng-container>

<tr mat-header-row *matHeaderRowDef="columnsToDisplay"></tr>
<tr
mat-row
*matRowDef="let element; columns: columnsToDisplay;"
class="example-element-row"
[class.example-expanded-row]="expandedElement === element"
></tr>
<tr
mat-row
*matRowDef="let row; columns: ['expandedDetail']"
class="example-detail-row"
></tr>
</table>


ts

import { SelectionModel } from '@angular/cdk/collections';
import { MatTableDataSource } from '@angular/material/table';
import { Component } from '@angular/core';
import { MatCheckboxModule } from '@angular/material/checkbox';
import {
animate,
state,
style,
transition,
trigger,
} from '@angular/animations';

/**
* @title Table with expandable rows
*/
@Component({
selector: 'table-expandable-rows-example',
styleUrls: ['table-expandable-rows-example.css'],
templateUrl: 'table-expandable-rows-example.html',
imports: [MatCheckboxModule],
animations: [
trigger('detailExpand', [
state('collapsed', style({ height: '0px', minHeight: '0' })),
state('expanded', style({ height: '*' })),
transition(
'expanded <=> collapsed',
animate('225ms cubic-bezier(0.4, 0.0, 0.2, 1)')
),
]),
],
})
export class TableExpandableRowsExample {
columnsToDisplay: string[] = [
'action',
'select',
'Name',
'weight',
'symbol',
'position',
];
dataSource = new MatTableDataSource<PeriodicElement> (ELEMENT_DATA);
expandedElement: PeriodicElement | null;
selection = new SelectionModel<PeriodicElement>(true, []);

/** Whether the number of selected elements matches the total number of rows. */
isAllSelected() {
const numSelected = this.selection.selected.length;
const numRows = this.dataSource.data.length;
return numSelected === numRows;
}

/** Selects all rows if they are not all selected; otherwise clear selection. */
toggleAllRows() {
if (this.isAllSelected()) {
this.selection.clear();
return;
}

this.selection.select(...this.dataSource.data);
}

/** The label for the checkbox on the passed row */
checkboxLabel(row?: PeriodicElement): string {
if (!row) {
return `${this.isAllSelected() ? 'deselect' : 'select'} all`;
}
return `${this.selection.isSelected(row) ? 'deselect' : 'select'} row ${
row.position + 1
}`;
}
}

export interface PeriodicElement {
Name: string;
position: number;
weight: number;
symbol: string;
description: string;
}

const ELEMENT_DATA: PeriodicElement[] = [
{
position: 1,
Name: 'Hydrogen',
weight: 1.0079,
symbol: 'H',
description: `Hydrogen is a chemical element with symbol H and atomic number 1. With a standard
atomic weight of 1.008, hydrogen is the lightest element on the periodic table.`,
},
{
position: 2,
Name: 'Helium',
weight: 4.0026,
symbol: 'He',
description: `Helium is a chemical element with symbol He and atomic number 2. It is a
colorless, odorless, tasteless, non-toxic, inert, monatomic gas, the first in the noble gas
group in the periodic table. Its boiling point is the lowest among all the elements.`,
},
{
position: 3,
Name: 'Lithium',
weight: 6.941,
symbol: 'Li',
description: `Lithium is a chemical element with symbol Li and atomic number 3. It is a soft,
silvery-white alkali metal. Under standard conditions, it is the lightest metal and the
lightest solid element.`,
},
];


My code is on StackBlitz. When I remove or comment out the mat-checkbox container the table will show but obviously when I re-add it or uncomment it. I need help on how I can get the checkbox to display on an expandable table with rows.

Continue reading...