CODEWITHSUNDEEP
angulartypescriptangular-forms
John Montgomery
John Montgomery

Reputation: 7096

Connect label to checkbox component

I created a custom checkbox component that looks like this:

checkbox.component.ts

import {Component, Input, OnInit, forwardRef} from "@angular/core"
import {ControlValueAccessor, NG_VALUE_ACCESSOR} from "@angular/forms"

@Component({
    selector: "checkbox",
    template: `
        <input type="checkbox" [checked]="checked" (change)="checkedChanged($event)" [id]="id">
        <label [for]="id"><span>{{checked ? "&#10003;" : "&nbsp;"}}</span></label>
    `,
    styles: [`
        input {
            opacity: 0;
            position: fixed;
        }
        label {
            line-height: 16px;
            height: 16px;
            width: 16px;
            border-radius: 5px;
            font-size: 16px;
            color: #000000;
            background-color: #ffffff;
            margin-bottom: 0;

            -webkit-touch-callout: none;
            -webkit-user-select: none;
            -khtml-user-select: none;
            -moz-user-select: none;
            -ms-user-select: none;
            user-select: none;
        }
    `],
    providers: [
        {
            provide: NG_VALUE_ACCESSOR,
            useExisting: forwardRef(() => CheckboxComponent),
            multi: true
        }
    ]
})
export class CheckboxComponent implements OnInit, ControlValueAccessor {
    static idCounter = 1

    @Input() id: string

    checked: boolean
    propagateChange = (_: any) => {}
    onTouchedCallback = () => {}

    ngOnInit () {
        // If an ID wasn't provided, generate a unique one
        if (!this.id) {
            this.id = "checkboxcomponent" + CheckboxComponent.idCounter++
        }
    }

    checkedChanged (event) {
        this.checked = event.target.checked
        this.propagateChange(event.target.checked)
    }

    // ControlValueAccessor requirements
    writeValue (value: any) {
        this.checked = value
    }
    registerOnChange (func: any) {
        this.propagateChange = func
    }
    registerOnTouched (func: any) {
        this.onTouchedCallback = func
    }
}

html example

<div class="col-4 text-right">
    <label for="foo">Foo:</label>
</div>
<div class="col-8">
    <checkbox [(ngModel)]="bar" id="foo"></checkbox>
</div>

The checkbox itself works perfectly, but the label doesn't. I wanted to pass in the ID as an input so I could connect it to an external label (the label positioning is different in different parts of the app, so I couldn't include it in the component), and inspecting the page shows that it's using the correct ID, but clicking the label doesn't toggle the checkbox. I assume it's some sort of scoping issue with the component, but I'm not sure how to handle that. Is there a way to make it work without having to add an extra (click) function or something every time I use it?

Upvotes: 1

Views: 641

Answers (1)

k.s.
k.s.

Reputation: 3004

If you change 

@Input id: string;

to 

@Input checkboxId: string;

and use it in <checkbox [(ngModel)]="bar" checkboxId="foo"></checkbox> it will work just fine.

https://stackblitz.com/edit/angular-qxjb4q

Upvotes: 4

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