docs(forms): add example apps for ngModelGroup (#11525)

modules/@angular/examples/forms/ts/ngModelGroup/e2e_test/ng_model_group_spec.ts

@@ -0,0 +1,41 @@
+/**
+ * @license
+ * Copyright 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 https://angular.io/license
+ */
+
+import {verifyNoBrowserErrors} from '../../../../_common/e2e_util';
+
+describe('ngModelGroup example', () => {
+  afterEach(verifyNoBrowserErrors);
+  let inputs: ElementFinder;
+  let buttons: ElementFinder;
+
+  beforeEach(() => {
+    browser.get('/forms/ts/ngModelGroup/index.html');
+    inputs = element.all(by.css('input'));
+    buttons = element.all(by.css('button'));
+  });
+
+  it('should populate the UI with initial values', () => {
+    expect(inputs.get(0).getAttribute('value')).toEqual('Nancy');
+    expect(inputs.get(1).getAttribute('value')).toEqual('Drew');
+  });
+
+  it('should show the error when name is invalid', () => {
+    inputs.get(0).click();
+    inputs.get(0).clear();
+    inputs.get(0).sendKeys('a');
+
+    expect(element(by.css('p')).getText()).toEqual('Name is invalid.');
+  });
+
+  it('should set the value when changing the domain model', () => {
+    buttons.get(1).click();
+    expect(inputs.get(0).getAttribute('value')).toEqual('Bess');
+    expect(inputs.get(1).getAttribute('value')).toEqual('Marvin');
+  });
+
+});

modules/@angular/examples/forms/ts/ngModelGroup/module.ts

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+/**
+ * @license
+ * Copyright 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 https://angular.io/license
+ */
+
+import {NgModule} from '@angular/core';
+import {FormsModule} from '@angular/forms';
+import {BrowserModule} from '@angular/platform-browser';
+import {NgModelGroupComp} from './ng_model_group_example';
+
+@NgModule({
+  imports: [BrowserModule, FormsModule],
+  declarations: [NgModelGroupComp],
+  bootstrap: [NgModelGroupComp]
+})
+export class AppModule {
+}

modules/@angular/examples/forms/ts/ngModelGroup/ng_model_group_example.ts

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+/**
+ * @license
+ * Copyright 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 https://angular.io/license
+ */
+
+// #docregion Component
+import {Component} from '@angular/core';
+import {NgForm} from '@angular/forms';
+
+@Component({
+  selector: 'example-app',
+  template: `
+    <form #f="ngForm" (ngSubmit)="onSubmit(f)">
+      <p *ngIf="nameCtrl.invalid">Name is invalid.</p>
+    
+      <div ngModelGroup="name" #nameCtrl="ngModelGroup">
+        <input name="first" [ngModel]="name.first" minlength="2">
+        <input name="last" [ngModel]="name.last" required>
+      </div>
+      
+      <input name="email" ngModel> 
+      <button>Submit</button>
+    </form>
+    
+    <button (click)="setValue()">Set value</button>
+  `,
+})
+export class NgModelGroupComp {
+  name = {first: 'Nancy', last: 'Drew'};
+
+  onSubmit(f: NgForm) {
+    console.log(f.value);  // {name: {first: 'Nancy', last: 'Drew'}, email: ''}
+    console.log(f.valid);  // true
+  }
+
+  setValue() { this.name = {first: 'Bess', last: 'Marvin'}; }
+}
+// #enddocregion