Angular 2 Custom Form Control example

app\app.component.ts

import { Component } from '@angular/core';
import { FormBuilder, FormGroup } from '@angular/forms';
import { createCounterRangeValidator } from './counter-input.component';

@Component({
  selector: 'my-app',
  template: `
    <h2>Inside Form</h2>
    <div>
      <label>Change min value:</label>
      <input [(ngModel)]="minValue">
    </div>
    <div>
      <label>Change max value:</label>
      <input [(ngModel)]="maxValue">
    </div>
    <form [formGroup]="form">
      <p>Control value: {{form.controls.counter.value}}</p>
      <p>Min Value: {{minValue}}</p>
      <p>Max Value: {{maxValue}}</p>
      <p>Form Value:</p>
      <pre>{{ form.value | json }}</pre>
      
      <counter-input
        formControlName="counter"
        [counterRangeMax]="maxValue"
        [counterRangeMin]="minValue"
        [counterValue]="50"
        ></counter-input>
    </form>

    <p *ngIf="!form.valid">Form is invalid!</p>

    
    <h2>Standalone</h2>
    <counter-input
      counterMinValue="0"
      counterMaxValue="3"
      [counterValue]="counterValue"></counter-input>
  `
})
export class AppComponent {

  form:FormGroup;
  counterValue = 3;
  minValue = 0;
  maxValue = 12;

  constructor(private fb: FormBuilder) {}

  ngOnInit() {
    this.form = this.fb.group({
      counter: this.counterValue
    });
  }

  // Remove comments to apply validation imperatively
  // Also remove [counterRangeMax|Min] from <custom-counter> to see effect
  /*
  ngOnInit() {
    this.form = this.fb.group({
      counter: [this.counterValue, createCounterRangeValidator(this.maxValue, this.minValue)]
    });
  }
  */
}

app\app.module.ts

import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { FormsModule, ReactiveFormsModule } from '@angular/forms';
import { AppComponent } from './app.component';
import { CounterInputComponent } from './counter-input.component.ts';

@NgModule({
  imports: [BrowserModule, FormsModule, ReactiveFormsModule],
  declarations: [AppComponent, CounterInputComponent],
  bootstrap: [AppComponent]
})
export class AppModule {}

app\counter-input.component.ts

import { Component, OnInit, forwardRef, Input, OnChanges } from '@angular/core';
import { FormControl, ControlValueAccessor, NG_VALUE_ACCESSOR, NG_VALIDATORS } from '@angular/forms';


export function createCounterRangeValidator(maxValue, minValue) {
  return (c: FormControl) => {
    let err = {
      rangeError: {
        given: c.value,
        max: maxValue || 10,
        min: minValue || 0
      }
    };

  return (c.value > +maxValue || c.value < +minValue) ? err: null;
  }
}

@Component({
  selector: 'counter-input',
  template: `
    <button (click)="increase()">+</button> {{counterValue}} <button (click)="decrease()">-</button>
  `,
  providers: [
    { provide: NG_VALUE_ACCESSOR, useExisting: forwardRef(() => CounterInputComponent), multi: true },
    { provide: NG_VALIDATORS, useExisting: forwardRef(() => CounterInputComponent), multi: true }
  ]
})
export class CounterInputComponent implements ControlValueAccessor, OnChanges {

  propagateChange:any = () => {};
  validateFn:any = () => {};
  
  @Input('counterValue') _counterValue = 0;
  @Input() counterRangeMax;
  @Input() counterRangeMin;

  get counterValue() {
    return this._counterValue;
  }
  
  set counterValue(val) {
    this._counterValue = val;
    this.propagateChange(val);
  }

  ngOnChanges(inputs) {
    if (inputs.counterRangeMax || inputs.counterRangeMin) {
      this.validateFn = createCounterRangeValidator(this.counterRangeMax, this.counterRangeMin);
    }
  }

  writeValue(value) {
    if (value) {
      this.counterValue = value;
    }
  }

  registerOnChange(fn) {
    this.propagateChange = fn;
  }

  registerOnTouched() {}

  increase() {
    this.counterValue++;
  }

  decrease() {
    this.counterValue--;
  }

  validate(c: FormControl) {
    return this.validateFn(c);
  }
}

app\main.ts

import { platformBrowserDynamic }    from '@angular/platform-browser-dynamic';
import { AppModule } from './app.module';

platformBrowserDynamic().bootstrapModule(AppModule);

index.html

<!DOCTYPE html>
<html>
  <head>
    <title>Angular 2 counter input contorl Demo by thoughtram</title>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <link rel="stylesheet" href="styles.css">

    <!-- 1. Load libraries -->
     <!-- Polyfill(s) for older browsers -->
    <script src="https://npmcdn.com/core-js/client/shim.min.js"></script>

    <script src="https://npmcdn.com/zone.js@0.6.12?main=browser"></script>
    <script src="https://npmcdn.com/reflect-metadata@0.1.3"></script>
    <script src="https://npmcdn.com/systemjs@0.19.27/dist/system.src.js"></script>

    <!-- 2. Configure SystemJS -->
    <script src="systemjs.config.js"></script>
    <script>
      System.import('app').catch(function(err){ console.error(err); });
    </script>
  </head>

  <!-- 3. Display the application -->
  <body>
    <my-app>Loading...</my-app>
  </body>
</html>

styles.css

/* Master Styles */
h1 {
  color: #369;
  font-family: Arial, Helvetica, sans-serif;
  font-size: 250%;
}
h2, h3 {
  color: #444;
  font-family: Arial, Helvetica, sans-serif;
  font-weight: lighter;
}
body {
  margin: 2em;
}
body, input[text], button {
  color: #888;
  font-family: Cambria, Georgia;
}
a {
  cursor: pointer;
  cursor: hand;
}
button {
  font-family: Arial;
  background-color: #eee;
  border: none;
  padding: 5px 10px;
  border-radius: 4px;
  cursor: pointer;
  cursor: hand;
}
button:hover {
  background-color: #cfd8dc;
}
button:disabled {
  background-color: #eee;
  color: #aaa;
  cursor: auto;
}

/* Navigation link styles */
nav a {
  padding: 5px 10px;
  text-decoration: none;
  margin-top: 10px;
  display: inline-block;
  background-color: #eee;
  border-radius: 4px;
}
nav a:visited, a:link {
  color: #607D8B;
}
nav a:hover {
  color: #039be5;
  background-color: #CFD8DC;
}
nav a.active {
  color: #039be5;
}

/* items class */
.items {
  margin: 0 0 2em 0;
  list-style-type: none;
  padding: 0;
  width: 24em;
}
.items li {
  cursor: pointer;
  position: relative;
  left: 0;
  background-color: #EEE;
  margin: .5em;
  padding: .3em 0;
  height: 1.6em;
  border-radius: 4px;
}
.items li:hover {
  color: #607D8B;
  background-color: #DDD;
  left: .1em;
}
.items li.selected:hover {
  background-color: #BBD8DC;
  color: white;
}
.items .text {
  position: relative;
  top: -3px;
}
.items {
  margin: 0 0 2em 0;
  list-style-type: none;
  padding: 0;
  width: 24em;
}
.items li {
  cursor: pointer;
  position: relative;
  left: 0;
  background-color: #EEE;
  margin: .5em;
  padding: .3em 0;
  height: 1.6em;
  border-radius: 4px;
}
.items li:hover {
  color: #607D8B;
  background-color: #DDD;
  left: .1em;
}
.items li.selected {
  background-color: #CFD8DC;
  color: white;
}

.items li.selected:hover {
  background-color: #BBD8DC;
}
.items .text {
  position: relative;
  top: -3px;
}
.items .badge {
  display: inline-block;
  font-size: small;
  color: white;
  padding: 0.8em 0.7em 0 0.7em;
  background-color: #607D8B;
  line-height: 1em;
  position: relative;
  left: -1px;
  top: -4px;
  height: 1.8em;
  margin-right: .8em;
  border-radius: 4px 0 0 4px;
}

/* everywhere else */
* {
  font-family: Arial, Helvetica, sans-serif;
}


/*
Copyright 2016 Google Inc. All Rights Reserved.
Use of this source code is governed by an MIT-style license that
can be found in the LICENSE file at http://angular.io/license
*/

systemjs.config.js

(function(global) {

  var ngVer = '@2.0.0-rc.5'; // lock in the angular package version; do not let it float to current!
  var routerVer = '@3.0.0-rc.1'; // lock router version
  var formsVer = '@0.3.0'; // lock forms version
  var routerDeprecatedVer = '@2.0.0-rc.2'; // temporarily until we update all the guides

  //map tells the System loader where to look for things
  var  map = {
    'app':                        'app',

    '@angular':                   'https://npmcdn.com/@angular', // sufficient if we didn't pin the version
    '@angular/router':            'https://npmcdn.com/@angular/router' + routerVer,
    '@angular/forms':             'https://npmcdn.com/@angular/forms' + formsVer,
    '@angular/router-deprecated': 'https://npmcdn.com/@angular/router-deprecated' + routerDeprecatedVer,
    'angular2-in-memory-web-api': 'https://npmcdn.com/angular2-in-memory-web-api', // get latest
    'rxjs':                       'https://npmcdn.com/rxjs@5.0.0-beta.6',
    'ts':                         'https://npmcdn.com/plugin-typescript@4.0.10/lib/plugin.js',
    'typescript':                 'https://npmcdn.com/typescript@1.9.0-dev.20160409/lib/typescript.js',
 };

  //packages tells the System loader how to load when no filename and/or no extension
  var packages = {
    'app':                        { main: 'main.ts',  defaultExtension: 'ts' },
    'rxjs':                       { defaultExtension: 'js' },
    'angular2-in-memory-web-api': { main: 'index.js', defaultExtension: 'js' },
  };

  var ngPackageNames = [
    'common',
    'compiler',
    'core',
    'http',
    'platform-browser',
    'platform-browser-dynamic',
    'upgrade',
  ];

  // Add map entries for each angular package
  // only because we're pinning the version with `ngVer`.
  ngPackageNames.forEach(function(pkgName) {
    map['@angular/'+pkgName] = 'https://npmcdn.com/@angular/' + pkgName + ngVer;
  });

  // Add package entries for angular packages
  ngPackageNames.forEach(function(pkgName) {

    // Bundled (~40 requests):
    packages['@angular/'+pkgName] = { main: '/bundles/' + pkgName + '.umd.js', defaultExtension: 'js' };

    // Individual files (~300 requests):
    //packages['@angular/'+pkgName] = { main: 'index.js', defaultExtension: 'js' };
  });

  // No umd for router yet
  packages['@angular/router'] = { main: 'index.js', defaultExtension: 'js' };

  // Forms not on rc yet
  packages['@angular/forms'] = { main: 'index.js', defaultExtension: 'js' };

  // Temporarily until we update the guides
  packages['@angular/router-deprecated'] = { main: '/bundles/router-deprecated' + '.umd.js', defaultExtension: 'js' };

  var config = {
    // DEMO ONLY! REAL CODE SHOULD NOT TRANSPILE IN THE BROWSER
    transpiler: 'ts',
    typescriptOptions: {
      tsconfig: true
    },
    meta: {
      'typescript': {
        "exports": "ts"
      }
    },
    map: map,
    packages: packages
  };

  System.config(config);

})(this);


/*
Copyright 2016 Google Inc. All Rights Reserved.
Use of this source code is governed by an MIT-style license that
can be found in the LICENSE file at http://angular.io/license
*/

tsconfig.json

{
  "compilerOptions": {
    "target": "es5",
    "module": "commonjs",
    "moduleResolution": "node",
    "sourceMap": true,
    "emitDecoratorMetadata": true,
    "experimentalDecorators": true,
    "removeComments": false,
    "noImplicitAny": true,
    "suppressImplicitAnyIndexErrors": true
  }
}