Custom validator for template driven forms validation

<!DOCTYPE html>
<html>

  <head>
    <base href="." />
    <title>angular2 playground</title>
    <link rel="stylesheet" href="style.css" />
    <script src="https://unpkg.com/zone.js/dist/zone.js"></script>
    <script src="https://unpkg.com/zone.js/dist/long-stack-trace-zone.js"></script>
    <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

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/bundles/core.umd.js',
    '@angular/common': 'npm:@angular/common/bundles/common.umd.js',
    '@angular/compiler': 'npm:@angular/compiler/bundles/compiler.umd.js',
    '@angular/platform-browser': 'npm:@angular/platform-browser/bundles/platform-browser.umd.js',
    '@angular/platform-browser-dynamic': 'npm:@angular/platform-browser-dynamic/bundles/platform-browser-dynamic.umd.js',
    '@angular/http': 'npm:@angular/http/bundles/http.umd.js',
    '@angular/router': 'npm:@angular/router/bundles/router.umd.js',
    '@angular/forms': 'npm:@angular/forms/bundles/forms.umd.js',
    
    '@angular/core/testing': 'npm:@angular/core/bundles/core-testing.umd.js',
    '@angular/common/testing': 'npm:@angular/common/bundles/common-testing.umd.js',
    '@angular/compiler/testing': 'npm:@angular/compiler/bundles/compiler-testing.umd.js',
    '@angular/platform-browser/testing': 'npm:@angular/platform-browser/bundles/platform-browser-testing.umd.js',
    '@angular/platform-browser-dynamic/testing': 'npm:@angular/platform-browser-dynamic/bundles/platform-browser-dynamic-testing.umd.js',
    '@angular/http/testing': 'npm:@angular/http/bundles/http-testing.umd.js',
    '@angular/router/testing': 'npm:@angular/router/bundles/router-testing.umd.js',
    
    'rxjs': 'npm:rxjs',
    'typescript': 'npm:typescript@2.0.2/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';

platformBrowserDynamic().bootstrapModule(AppModule)

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

import { JuriNameValidator } from './juriName.validator';

@Component({
  selector: 'my-app',
  template: `
    <div>
      <h2>Custom validator for template driven forms validation</h2>
      <form #form="ngForm" (ngSubmit)="form.valid && onSubmit(form.value)">
        <div>
          Firstname: 
          <input type="text" ngModel name="firstname" #firstname="ngModel" required juriName />
          <div style="color:red" *ngIf="firstname.errors && (firstname.dirty || firstname.touched || form.submitted)">
            <p *ngIf="firstname.errors.required">
              The name is required
            </p>
            <p *ngIf="firstname.errors.juriName">
              Only allowed name is "Juri" ;)
            </p>
          </div>
        </div>
        <div>
          <button>Submit</button>
          <button type="reset" (click)="onReset($event, form)">reset</button>
        </div>
      </form>
    </div>
    
    <hr>
    
    <pre>Is form valid: <br>{{form.valid | json}}</pre>
    <pre>Is form submitted: <br>{{form.submitted | json}}</pre>
    <pre>form value: <br>{{form.value | json}}</pre>
    
    <hr>
    
    <h2>Output:</h2>
    
    <pre *ngIf="submittedValue">{{ submittedValue | json }}</pre>
    
  `,
})
export class App {
  submittedValue;
  
  constructor() {
  
  }
  
  onSubmit(value) {
    this.submittedValue = value;
  }
  
  onReset() {
    this.submittedValue = null;
  }
  
}

@NgModule({
  imports: [ BrowserModule, FormsModule ],
  declarations: [ App, JuriNameValidator ],
  bootstrap: [ App ]
})
export class AppModule {}

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


// validation function
function validateJuriNameFactory() : ValidatorFn {
  return (c: AbstractControl) => {
    
    let isValid = c.value === 'Juri';
    
    if(isValid) {
      return null;
    } else {
      return {
        juriName: {
          valid: false
        }
      };
    }

  }
}


@Directive({
  selector: '[juriName][ngModel]',
  providers: [
    { provide: NG_VALIDATORS, useExisting: JuriNameValidator, multi: true }
  ]
})
export class JuriNameValidator implements Validator {
  validator: ValidatorFn;
  
  constructor() {
    this.validator = validateJuriNameFactory();
  }
  
  validate(c: FormControl) {
    return this.validator(c);
  }
  
}