feat(forms): easier updating of validators on existing controls

modules/@angular/forms/src/model.ts

@@ -100,6 +100,18 @@ export abstract class AbstractControl {
 
   get pending(): boolean { return this._status == PENDING; }
 
+  setAsyncValidators(newValidator: AsyncValidatorFn|AsyncValidatorFn[]): void {
+    this.asyncValidator = coerceToAsyncValidator(newValidator);
+  }
+
+  clearAsyncValidators(): void { this.asyncValidator = null; }
+
+  setValidators(newValidator: ValidatorFn|ValidatorFn[]): void {
+    this.validator = coerceToValidator(newValidator);
+  }
+
+  clearValidators(): void { this.validator = null; }
+
   markAsTouched(): void { this._touched = true; }
 
   markAsDirty({onlySelf}: {onlySelf?: boolean} = {}): void {

modules/@angular/forms/test/model_spec.ts

@@ -65,6 +65,57 @@ export function main() {
           var c = new FormControl(null, Validators.required);
           expect(c.errors).toEqual({'required': true});
         });
+
+        it('should set single validator', () => {
+          var c = new FormControl(null);
+          expect(c.valid).toEqual(true);
+
+          c.setValidators(Validators.required);
+
+          c.updateValue(null);
+          expect(c.valid).toEqual(false);
+
+          c.updateValue('abc');
+          expect(c.valid).toEqual(true);
+        });
+
+        it('should set multiple validators from array', () => {
+          var c = new FormControl('');
+          expect(c.valid).toEqual(true);
+
+          c.setValidators([Validators.minLength(5), Validators.required]);
+
+          c.updateValue('');
+          expect(c.valid).toEqual(false);
+
+          c.updateValue('abc');
+          expect(c.valid).toEqual(false);
+
+          c.updateValue('abcde');
+          expect(c.valid).toEqual(true);
+        });
+
+        it('should clear validators', () => {
+          var c = new FormControl('', Validators.required);
+          expect(c.valid).toEqual(false);
+
+          c.clearValidators();
+          expect(c.validator).toEqual(null);
+
+          c.updateValue('');
+          expect(c.valid).toEqual(true);
+        });
+
+        it('should add after clearing', () => {
+          var c = new FormControl('', Validators.required);
+          expect(c.valid).toEqual(false);
+
+          c.clearValidators();
+          expect(c.validator).toEqual(null);
+
+          c.setValidators([Validators.required]);
+          expect(c.validator).not.toBe(null);
+        });
       });
 
       describe('asyncValidator', () => {
@@ -135,6 +186,38 @@ export function main() {
 
              expect(c.errors).toEqual({'async': true, 'other': true});
            }));
+
+        it('should add single async validator', fakeAsync(() => {
+             var c = new FormControl('value', null);
+
+             c.setAsyncValidators(asyncValidator('expected'));
+             expect(c.asyncValidator).not.toEqual(null);
+
+             c.updateValue('expected');
+             tick();
+
+             expect(c.valid).toEqual(true);
+           }));
+
+        it('should add async validator from array', fakeAsync(() => {
+             var c = new FormControl('value', null);
+
+             c.setAsyncValidators([asyncValidator('expected')]);
+             expect(c.asyncValidator).not.toEqual(null);
+
+             c.updateValue('expected');
+             tick();
+
+             expect(c.valid).toEqual(true);
+           }));
+
+        it('should clear async validators', fakeAsync(() => {
+             var c = new FormControl('value', [asyncValidator('expected'), otherAsyncValidator]);
+
+             c.clearValidators();
+
+             expect(c.asyncValidator).toEqual(null);
+           }));
       });
 
       describe('dirty', () => {