fix(input): ensure that property bindings works

* Developers are currently not able to use property bindings for `required`, `disabled`, `type` and `placeholder`.
* This commit ensures that the Angular input setters are in sync with the native input element.
* Adds test to ensure that the property bindings work for the native input element (and not for the component instance as before)

Fixes angular#2428

src/lib/input/input-container.spec.ts

@@ -41,6 +41,8 @@ describe('MdInputContainer', function () {
         MdInputContainerZeroTestController,
         MdTextareaWithBindings,
         MdInputContainerWithDisabled,
+        MdInputContainerWithRequired,
+        MdInputContainerWithType,
         MdInputContainerMissingMdInputTestController
       ],
     });
@@ -236,16 +238,20 @@ describe('MdInputContainer', function () {
     let fixture = TestBed.createComponent(MdInputContainerPlaceholderAttrTestComponent);
     fixture.detectChanges();
 
-    let el = fixture.debugElement.query(By.css('label'));
-    expect(el).toBeNull();
+    let inputEl = fixture.debugElement.query(By.css('input')).nativeElement;
+
+    expect(fixture.debugElement.query(By.css('label'))).toBeNull();
+    expect(inputEl.placeholder).toBe('');
 
     fixture.componentInstance.placeholder = 'Other placeholder';
     fixture.detectChanges();
 
-    el = fixture.debugElement.query(By.css('label'));
-    expect(el).not.toBeNull();
-    expect(el.nativeElement.textContent).toMatch('Other placeholder');
-    expect(el.nativeElement.textContent).not.toMatch(/\*/g);
+    let labelEl = fixture.debugElement.query(By.css('label'));
+
+    expect(inputEl.placeholder).toBe('Other placeholder');
+    expect(labelEl).not.toBeNull();
+    expect(labelEl.nativeElement.textContent).toMatch('Other placeholder');
+    expect(labelEl.nativeElement.textContent).not.toMatch(/\*/g);
   }));
 
   it('supports placeholder element', async(() => {
@@ -274,18 +280,51 @@ describe('MdInputContainer', function () {
     expect(el.nativeElement.textContent).toMatch(/hello\s+\*/g);
   });
 
-  it('supports the disabled attribute', async(() => {
+  it('supports the disabled attribute as binding', async(() => {
     let fixture = TestBed.createComponent(MdInputContainerWithDisabled);
     fixture.detectChanges();
 
     let underlineEl = fixture.debugElement.query(By.css('.md-input-underline')).nativeElement;
+    let inputEl = fixture.debugElement.query(By.css('input')).nativeElement;
+
     expect(underlineEl.classList.contains('md-disabled')).toBe(false, 'should not be disabled');
+    expect(inputEl.disabled).toBe(false);
 
     fixture.componentInstance.disabled = true;
     fixture.detectChanges();
+
+    expect(inputEl.disabled).toBe(true);
     expect(underlineEl.classList.contains('md-disabled')).toBe(true, 'should be disabled');
   }));
 
+  it('supports the required attribute as binding', async(() => {
+    let fixture = TestBed.createComponent(MdInputContainerWithRequired);
+    fixture.detectChanges();
+
+    let inputEl = fixture.debugElement.query(By.css('input')).nativeElement;
+
+    expect(inputEl.required).toBe(false);
+
+    fixture.componentInstance.required = true;
+    fixture.detectChanges();
+
+    expect(inputEl.required).toBe(true);
+  }));
+
+  it('supports the type attribute as binding', async(() => {
+    let fixture = TestBed.createComponent(MdInputContainerWithType);
+    fixture.detectChanges();
+
+    let inputEl = fixture.debugElement.query(By.css('input')).nativeElement;
+
+    expect(inputEl.type).toBe('text');
+
+    fixture.componentInstance.type = 'password';
+    fixture.detectChanges();
+
+    expect(inputEl.type).toBe('password');
+  }));
+
   it('supports textarea', () => {
     let fixture = TestBed.createComponent(MdTextareaWithBindings);
     fixture.detectChanges();
@@ -310,6 +349,20 @@ class MdInputContainerWithDisabled {
   disabled: boolean;
 }
 
+@Component({
+  template: `<md-input-container><input md-input [required]="required"></md-input-container>`
+})
+class MdInputContainerWithRequired {
+  required: boolean;
+}
+
+@Component({
+  template: `<md-input-container><input md-input [type]="type"></md-input-container>`
+})
+class MdInputContainerWithType {
+  type: string;
+}
+
 @Component({
   template: `<md-input-container><input md-input required placeholder="hello"></md-input-container>`
 })

src/lib/input/input-container.ts

@@ -71,53 +71,71 @@ export class MdHint {
   selector: 'input[md-input], textarea[md-input], input[mat-input], textarea[mat-input]',
   host: {
     'class': 'md-input-element',
+    // Native input properties that are overwritten by Angular inputs need to be synced with
+    // the native input element. Otherwise property bindings for those don't work.
     '[id]': 'id',
+    '[placeholder]': 'placeholder',
+    '[disabled]': 'disabled',
+    '[required]': 'required',
     '(blur)': '_onBlur()',
     '(focus)': '_onFocus()',
     '(input)': '_onInput()',
   }
 })
 export class MdInputDirective implements AfterContentInit {
+
+  /** Variables used as cache for getters and setters. */
+  private _type = 'text';
+  private _placeholder: string = '';
+  private _disabled = false;
+  private _required = false;
+  private _id: string;
+  private _cachedUid: string;
+
+  /** The element's value. */
+  value: any;
+
+  /** Whether the element is focused or not. */
+  focused = false;
+
   /** Whether the element is disabled. */
   @Input()
   get disabled() { return this._disabled; }
   set disabled(value: any) { this._disabled = coerceBooleanProperty(value); }
-  private _disabled = false;
 
   /** Unique id of the element. */
   @Input()
   get id() { return this._id; };
-  set id(value: string) { this._id = value || this._uid; }
-  private _id: string;
+  set id(value: string) {this._id = value || this._uid; }
 
   /** Placeholder attribute of the element. */
   @Input()
   get placeholder() { return this._placeholder; }
   set placeholder(value: string) {
-    if (this._placeholder != value) {
+    if (this._placeholder !== value) {
       this._placeholder = value;
       this._placeholderChange.emit(this._placeholder);
     }
   }
-  private _placeholder = '';
-
   /** Whether the element is required. */
   @Input()
   get required() { return this._required; }
   set required(value: any) { this._required = coerceBooleanProperty(value); }
-  private _required = false;
 
   /** Input type of the element. */
   @Input()
   get type() { return this._type; }
   set type(value: string) {
     this._type = value || 'text';
     this._validateType();
-  }
-  private _type = 'text';
 
-  /** The element's value. */
-  value: any;
+    // When using Angular inputs, developers are no longer able to set the properties on the native
+    // input element. To ensure that bindings for `type` work, we need to sync the setter
+    // with the native property. Textarea elements don't support the type property or attribute.
+    if (!this._isTextarea()) {
+      this._renderer.setElementProperty(this._elementRef.nativeElement, 'type', this._type);
+    }
+  }
 
   /**
    * Emits an event when the placeholder changes so that the `md-input-container` can re-validate.
@@ -126,10 +144,7 @@ export class MdInputDirective implements AfterContentInit {
 
   get empty() { return (this.value == null || this.value === '') && !this._isNeverEmpty(); }
 
-  focused = false;
-
   private get _uid() { return this._cachedUid = this._cachedUid || `md-input-${nextUniqueId++}`; }
-  private _cachedUid: string;
 
   private _neverEmptyInputTypes = [
     'date',
@@ -168,12 +183,23 @@ export class MdInputDirective implements AfterContentInit {
 
   /** Make sure the input is a supported type. */
   private _validateType() {
-    if (MD_INPUT_INVALID_TYPES.indexOf(this._type) != -1) {
+    if (MD_INPUT_INVALID_TYPES.indexOf(this._type) !== -1) {
       throw new MdInputContainerUnsupportedTypeError(this._type);
     }
   }
 
-  private _isNeverEmpty() { return this._neverEmptyInputTypes.indexOf(this._type) != -1; }
+  private _isNeverEmpty() { return this._neverEmptyInputTypes.indexOf(this._type) !== -1; }
+
+  /** Determines if the component host is a textarea. If not recognizable it returns false. */
+  private _isTextarea() {
+    let nativeElement = this._elementRef.nativeElement;
+    return nativeElement ? nativeElement.nodeName === 'textarea' : 'input';
+  }
+
+  /** Sets a property on the native input element. */
+  private _setElementProperty(property: string, value: any) {
+    this._renderer.setElementProperty(this._elementRef.nativeElement, property, value);
+  }
 }