egghead.io: Create a custom validator for template driven forms in Angular

<!DOCTYPE html>
<html>

  <head>
    <base href="." />
    <script type="text/javascript" charset="utf-8">
      window.AngularVersionForThisPlunker = 'latest'
    </script>
    <title>angular playground</title>
    <link rel="stylesheet" href="style.css" />
    <script src="https://unpkg.com/core-js@2.4.1/client/shim.min.js"></script>
    <script src="https://unpkg.com/zone.js/dist/zone.js"></script>
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    <script src="https://unpkg.com/reflect-metadata@0.1.3/Reflect.js"></script>
    <script src="https://unpkg.com/systemjs@0.19.31/dist/system.js"></script>
    <script src="config.js"></script>
    <script>
    System.import('app')
      .catch(console.error.bind(console));
  </script>
  </head>

  <body>
    <my-app>
    loading...
  </my-app>
  </body>

</html>

/* Styles go here */

### Angular Starter Plunker - Typescript

var angularVersion;
if(window.AngularVersionForThisPlunker === 'latest'){
  angularVersion = ''; //picks up latest
}
else {
  angularVersion = '@' + window.AngularVersionForThisPlunker;
}

System.config({
  //use typescript for compilation
  transpiler: 'typescript',
  //typescript compiler options
  typescriptOptions: {
    emitDecoratorMetadata: true
  },
  paths: {
    'npm:': 'https://unpkg.com/'
  },
  //map tells the System loader where to look for things
  map: {
    
    'app': './src',
    '@angular/core': 'npm:@angular/core'+ angularVersion + '/bundles/core.umd.js',
    '@angular/common': 'npm:@angular/common' + angularVersion + '/bundles/common.umd.js',
    '@angular/common/http': 'npm:@angular/common' + angularVersion + '/bundles/common-http.umd.js',
    '@angular/compiler': 'npm:@angular/compiler' + angularVersion  + '/bundles/compiler.umd.js',
    '@angular/platform-browser': 'npm:@angular/platform-browser' + angularVersion + '/bundles/platform-browser.umd.js',
    '@angular/platform-browser-dynamic': 'npm:@angular/platform-browser-dynamic' + angularVersion + '/bundles/platform-browser-dynamic.umd.js',
    '@angular/http': 'npm:@angular/http' + angularVersion + '/bundles/http.umd.js',
    '@angular/router': 'npm:@angular/router' + angularVersion +'/bundles/router.umd.js',
    '@angular/forms': 'npm:@angular/forms' + angularVersion + '/bundles/forms.umd.js',
    '@angular/animations': 'npm:@angular/animations' + angularVersion + '/bundles/animations.umd.js',
    '@angular/platform-browser/animations': 'npm:@angular/platform-browser' + angularVersion + '/bundles/platform-browser-animations.umd.js',
    '@angular/animations/browser': 'npm:@angular/animations' + angularVersion + '/bundles/animations-browser.umd.js',
    
    '@angular/core/testing': 'npm:@angular/core' + angularVersion + '/bundles/core-testing.umd.js',
    '@angular/common/testing': 'npm:@angular/common' + angularVersion + '/bundles/common-testing.umd.js',
    '@angular/common/http/testing': 'npm:@angular/common' + angularVersion + '/bundles/common-http-testing.umd.js',
    '@angular/compiler/testing': 'npm:@angular/compiler' + angularVersion + '/bundles/compiler-testing.umd.js',
    '@angular/platform-browser/testing': 'npm:@angular/platform-browser' + angularVersion + '/bundles/platform-browser-testing.umd.js',
    '@angular/platform-browser-dynamic/testing': 'npm:@angular/platform-browser-dynamic' + angularVersion + '/bundles/platform-browser-dynamic-testing.umd.js',
    '@angular/http/testing': 'npm:@angular/http' + angularVersion + '/bundles/http-testing.umd.js',
    '@angular/router/testing': 'npm:@angular/router' + angularVersion + '/bundles/router-testing.umd.js',
    'tslib': 'npm:tslib@1.6.1',
    'rxjs': 'npm:rxjs',
    'typescript': 'npm:typescript@2.2.1/lib/typescript.js'
  },
  //packages defines our app package
  packages: {
    app: {
      main: './main.ts',
      defaultExtension: 'ts'
    },
    rxjs: {
      defaultExtension: 'js'
    }
  }
});

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

platformBrowserDynamic().bootstrapModule(AppModule)

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

@Component({
  selector: 'my-app',
  template: `
    <h1>Custom validator - Template driven forms</h1>
    <person-edit></person-edit>
  `
})
export class AppComponent {}

import { ValidatorFn, ValidationErrors, AbstractControl } from '@angular/forms';

export function nameValidator(name: string): ValidatorFn {
  return (control: AbstractControl): ValidationErrors | null => {
    const isValid = control.value === '' || control.value === name;

    if (isValid) {
      return null;
    } else {
      return {
        nameMatch: {
          allowedName: name
        }
      };
    }
  };
}

import { Validator, FormControl, NG_VALIDATORS } from '@angular/forms';
import { Directive, Input } from '@angular/core';

import { nameValidator } from './name.validator';

@Directive({
  selector: '[nameMatch][ngModel]',
  providers: [{ provide: NG_VALIDATORS, useExisting: NameMatchValidatorDirective, multi: true }]
})
export class NameMatchValidatorDirective implements Validator {
  @Input() nameMatch;
  validate(c: FormControl) {
    return nameValidator(this.nameMatch)(c);
  }
}

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

@Component({
  selector: 'person-edit',
  template: `
    <form novalidate #form="ngForm" (ngSubmit)="onSubmit(form)">
        <div>
          Firstname:
          <input type="text"
             ngModel
             #firstname="ngModel"
             name="firstname"
             required
             [nameMatch]="validName" />
          <div class="error" *ngIf="firstname.invalid && (firstname.dirty || firstname.touched)">
            <div *ngIf="firstname.errors.required">
              You have to provide a name.
            </div>
            <div *ngIf="firstname.errors.nameMatch">
              You have to specify a matching name such as "{{ firstname.errors.nameMatch.allowedName }}"
            </div>
          </div>
        </div>
        <button type="submit">Save</button>
    </form>
  `,
  styles: [
    `
      .error { color: red }
    `
  ]
})
export class PersonEditComponent {
  validName = 'jack';
  onSubmit({ value, valid }) {
    console.log(value, valid);
  }
}

//our root app component
import { NgModule } from '@angular/core';
import { FormsModule } from '@angular/forms';
import {BrowserModule} from '@angular/platform-browser'

import { AppComponent } from './app.component';
import { PersonEditComponent } from './person-edit.component';
import { NameMatchValidatorDirective } from './nameValidator.directive';

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