Using NgModel with a custom element

Question

Using NgModel with a custom element

I am currently using a basic component within my form as shown below:

<app-slider [min]="field.min" [max]="field.max" [value]="field.min"></app-slider>

This component consists of the following code:

HTML:

<input #mySlider
       class="slider"
       type="text"
       name="slider"
       data-provide="slider"
       data-slider-min="1"
       data-slider-max="3"
       [attr.data-slider-min]="min"
       [attr.data-slider-max]="max"
       data-slider-step="1"
       [attr.data-slider-value]="value"
       data-slider-tooltip="show"/>

TypeScript (ts):

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

declare var $ : any;

@Component({
    selector: 'app-slider',
    templateUrl: './slider.component.html',
    styleUrls: ['./slider.component.css']
})
export class SliderComponent{
    @ViewChild('mySlider') slider: any; // can be ElementRef;
    @Input() min: number;
    @Input() max: number;
    @Input() value: number;

    constructor() { }

    ngAfterViewInit() {
        // slider is available
        $(this.slider.nativeElement).slider();
        let value = $(this.slider.nativeElement).attr("data-slider-value");
        $(this.slider.nativeElement).slider('setValue', value);
    }
}

I would like to implement NgModel on my component in order to access and modify its value:

<app-slider [min]="field.min" [max]="field.max" [value]="field.min" [(ngModel)]="currentValue"></app-slider>

Is there a way for me to accomplish this?

angular typescript

Answer 1

Answer №1

Introduction: it appears that a jQuery UI slider-like tool is being utilized, albeit with some modifications. In instances where assumptions had to be made, the API of this tool was employed.

The main objective achieved here is through the implementation of ControlValueAccessor, allowing the component to be recognized by Angular as a form control or, in simpler terms, a custom form control. While I am unsure if the syntax aligns with the latest Angular practices, my approach usually looked something like this:

import { Component, ViewChild, Input, EventEmitter, forwardRef } from '@angular/core';
import { ControlValueAccessor, NG_VALUE_ACCESSOR } from '@angular/forms';

declare var $: any;

export const SLIDER_VALUE_ACCESSOR: any = {
    provide: NG_VALUE_ACCESSOR,
    useExisting: forwardRef(() => SliderComponent),
    multi: true
};

@Component({
    selector: 'app-slider',
    templateUrl: './slider.component.html',
    styleUrls: ['./slider.component.css'],
    providers: [
        SLIDER_VALUE_ACCESSOR
    ]
})
export class SliderComponent implements ControlValueAccessor {
    @ViewChild('mySlider') slider: any;
    @Input() min: number;
    @Input() max: number;

    propagateChange = (_: any) => { };
    propagateTouched = () => { };

    constructor() { }

    ngAfterViewInit() {
        $(this.slider.nativeElement).slider();
    }

    onChange() {
        this.propagateChange($(this.slider.nativeElement).attr("data-slider-value"););
    }

    writeValue(value: any): void {
        $(this.slider.nativeElement).slider('setValue', value);
    }

    registerOnChange(fn: any): void {
        this.propagateChange = fn;
    }

    registerOnTouched(fn: any): void {
        this.propagateTouched = fn;
    }

    setDisabledState?(isDisabled: boolean): void {
        $(this.slider.nativeElement).slider(isDisabled ? "disable" : "enable");
    }
}

Template structure:

<input #mySlider
    class="slider"
    type="text"
    name="slider"
    data-provide="slider"
    data-slider-min="1"
    data-slider-max="3"
    [attr.data-slider-min]="min"
    [attr.data-slider-max]="max"
    data-slider-step="1"
    data-slider-tooltip="show"
    (change)="onChange" /> <!-- change event resembling jQuery UI slider  -->

Implementation example:

<app-slider [min]="field.min" [max]="field.max" [(ngModel)]="currentValue"></app-slider>

In this scenario, currentValue must be initialized with the minimum value for proper functionality based on the given example.

Answer 2

Introduction: it appears that a jQuery UI slider-like tool is being utilized, albeit with some modifications. In instances where assumptions had to be made, the API of this tool was employed.

The main objective achieved here is through the implementation of ControlValueAccessor, allowing the component to be recognized by Angular as a form control or, in simpler terms, a custom form control. While I am unsure if the syntax aligns with the latest Angular practices, my approach usually looked something like this:

import { Component, ViewChild, Input, EventEmitter, forwardRef } from '@angular/core';
import { ControlValueAccessor, NG_VALUE_ACCESSOR } from '@angular/forms';

declare var $: any;

export const SLIDER_VALUE_ACCESSOR: any = {
    provide: NG_VALUE_ACCESSOR,
    useExisting: forwardRef(() => SliderComponent),
    multi: true
};

@Component({
    selector: 'app-slider',
    templateUrl: './slider.component.html',
    styleUrls: ['./slider.component.css'],
    providers: [
        SLIDER_VALUE_ACCESSOR
    ]
})
export class SliderComponent implements ControlValueAccessor {
    @ViewChild('mySlider') slider: any;
    @Input() min: number;
    @Input() max: number;

    propagateChange = (_: any) => { };
    propagateTouched = () => { };

    constructor() { }

    ngAfterViewInit() {
        $(this.slider.nativeElement).slider();
    }

    onChange() {
        this.propagateChange($(this.slider.nativeElement).attr("data-slider-value"););
    }

    writeValue(value: any): void {
        $(this.slider.nativeElement).slider('setValue', value);
    }

    registerOnChange(fn: any): void {
        this.propagateChange = fn;
    }

    registerOnTouched(fn: any): void {
        this.propagateTouched = fn;
    }

    setDisabledState?(isDisabled: boolean): void {
        $(this.slider.nativeElement).slider(isDisabled ? "disable" : "enable");
    }
}

Template structure:

<input #mySlider
    class="slider"
    type="text"
    name="slider"
    data-provide="slider"
    data-slider-min="1"
    data-slider-max="3"
    [attr.data-slider-min]="min"
    [attr.data-slider-max]="max"
    data-slider-step="1"
    data-slider-tooltip="show"
    (change)="onChange" /> <!-- change event resembling jQuery UI slider  -->

Implementation example:

<app-slider [min]="field.min" [max]="field.max" [(ngModel)]="currentValue"></app-slider>

In this scenario, currentValue must be initialized with the minimum value for proper functionality based on the given example.

Answer 3

Answer №2

Give this a shot:

<app-slider [min]="field.min" [max]="field.max" [(value)]="currentValue"></app-slider>

Update the value of currentValue using changeCurrentValue

import {Component, ViewChild, Input, Output, EventEmitter} from '@angular/core';

declare var $ : any;

@Component({
    selector: 'app-slider',
    templateUrl: './slider.component.html',
    styleUrls: ['./slider.component.css']
})
export class SliderComponent{
    @ViewChild('mySlider') slider: any; // can be ElementRef;
    @Input() min: number;
    @Input() max: number;
    @Input() value: number;
    @Output() valueChange = new EventEmitter();
    constructor() { }

    ngAfterViewInit() {
         let self = this;
        // slider is ready
        $(this.slider.nativeElement).slider();
        let value = $(this.slider.nativeElement).attr("data-slider-value");
        $(this.slider.nativeElement).slider('setValue', value);

       $(this.slider.nativeElement).slider().on('change', function(event) {
          self.value = event.value.newValue; self.valueChange.emit(self.value); });
          }

   changeCurrentValue(){
      this.value= //insert desired value;
      this.valueChange.emit(this.value);
   } 
}

Answer 4

Give this a shot:

<app-slider [min]="field.min" [max]="field.max" [(value)]="currentValue"></app-slider>

Update the value of currentValue using changeCurrentValue

import {Component, ViewChild, Input, Output, EventEmitter} from '@angular/core';

declare var $ : any;

@Component({
    selector: 'app-slider',
    templateUrl: './slider.component.html',
    styleUrls: ['./slider.component.css']
})
export class SliderComponent{
    @ViewChild('mySlider') slider: any; // can be ElementRef;
    @Input() min: number;
    @Input() max: number;
    @Input() value: number;
    @Output() valueChange = new EventEmitter();
    constructor() { }

    ngAfterViewInit() {
         let self = this;
        // slider is ready
        $(this.slider.nativeElement).slider();
        let value = $(this.slider.nativeElement).attr("data-slider-value");
        $(this.slider.nativeElement).slider('setValue', value);

       $(this.slider.nativeElement).slider().on('change', function(event) {
          self.value = event.value.newValue; self.valueChange.emit(self.value); });
          }

   changeCurrentValue(){
      this.value= //insert desired value;
      this.valueChange.emit(this.value);
   } 
}

Using NgModel with a custom element

Answer №1

Answer №2

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