feat(forms): implements a combinator for composing async validators

modules/angular2/src/core/forms/validators.ts

@@ -3,6 +3,7 @@ import {ListWrapper, StringMapWrapper} from 'angular2/src/core/facade/collection
 import {OpaqueToken} from 'angular2/src/core/di';
 
 import * as modelModule from './model';
+import {PromiseWrapper} from "../facade/promise";
 
 /**
  * Providers for validators to be used for {@link Control}s in a form.
@@ -18,6 +19,7 @@ import * as modelModule from './model';
  * ```
  */
 export const NG_VALIDATORS: OpaqueToken = CONST_EXPR(new OpaqueToken("NgValidators"));
+export const NG_ASYNC_VALIDATORS: OpaqueToken = CONST_EXPR(new OpaqueToken("NgAsyncValidators"));
 
 /**
  * Provides a set of validators used by form controls.
@@ -76,14 +78,33 @@ export class Validators {
    * of the individual error maps.
    */
   static compose(validators: Function[]): Function {
-    if (isBlank(validators)) return Validators.nullValidator;
+    if (isBlank(validators)) return null;
+    var presentValidators = ListWrapper.filter(validators, isPresent);
+    if (presentValidators.length == 0) return null;
 
     return function(control: modelModule.AbstractControl) {
-      var res = ListWrapper.reduce(validators, (res, validator) => {
-        var errors = isPresent(validator) ? validator(control) : null;
-        return isPresent(errors) ? StringMapWrapper.merge(<any>res, <any>errors) : res;
-      }, {});
-      return StringMapWrapper.isEmpty(res) ? null : res;
+      return _mergeErrors(_executeValidators(control, presentValidators));
+    };
+  }
+
+  static composeAsync(validators: Function[]): Function {
+    if (isBlank(validators)) return null;
+    var presentValidators = ListWrapper.filter(validators, isPresent);
+    if (presentValidators.length == 0) return null;
+
+    return function(control: modelModule.AbstractControl) {
+      return PromiseWrapper.all(_executeValidators(control, presentValidators)).then(_mergeErrors);
     };
   }
 }
+
+function _executeValidators(control: modelModule.AbstractControl, validators: Function[]): any[] {
+  return validators.map(v => v(control));
+}
+
+function _mergeErrors(arrayOfErrors: any[]): {[key: string]: any} {
+  var res = ListWrapper.reduce(arrayOfErrors, (res, errors) => {
+    return isPresent(errors) ? StringMapWrapper.merge(<any>res, <any>errors) : res;
+  }, {});
+  return StringMapWrapper.isEmpty(res) ? null : res;
+}

modules/angular2/test/core/forms/validators_spec.ts

@@ -7,9 +7,14 @@ import {
   expect,
   beforeEach,
   afterEach,
+  fakeAsync,
+  tick,
   el
 } from 'angular2/testing_internal';
 import {ControlGroup, Control, Validators, AbstractControl, ControlArray} from 'angular2/core';
+import {PromiseWrapper} from 'angular2/src/core/facade/promise';
+import {TimerWrapper} from 'angular2/src/core/facade/async';
+import {CONST_EXPR} from 'angular2/src/core/facade/lang';
 
 export function main() {
   function validator(key: string, error: any) {
@@ -65,8 +70,8 @@ export function main() {
     });
 
     describe("compose", () => {
-      it("should return a null validator when given null",
-         () => { expect(Validators.compose(null)).toBe(Validators.nullValidator); });
+      it("should return null when given null",
+         () => { expect(Validators.compose(null)).toBe(null); });
 
       it("should collect errors from all the validators", () => {
         var c = Validators.compose([validator("a", true), validator("b", true)]);
@@ -88,5 +93,55 @@ export function main() {
         expect(c(new Control(""))).toEqual({"required": true});
       });
     });
+
+    describe("composeAsync", () => {
+      function asyncValidator(expected, response, timeout = 0) {
+        return (c) => {
+          var completer = PromiseWrapper.completer();
+          var res = c.value != expected ? response : null;
+          TimerWrapper.setTimeout(() => { completer.resolve(res); }, timeout);
+          return completer.promise;
+        };
+      }
+
+      it("should return null when given null",
+         () => { expect(Validators.composeAsync(null)).toEqual(null); });
+
+      it("should collect errors from all the validators", fakeAsync(() => {
+           var c = Validators.composeAsync([
+             asyncValidator("expected", {"one": true}),
+             asyncValidator("expected", {"two": true})
+           ]);
+
+           var value = null;
+           c(new Control("invalid")).then(v => value = v);
+
+           tick(1);
+
+           expect(value).toEqual({"one": true, "two": true});
+         }));
+
+      it("should return null when no errors", fakeAsync(() => {
+           var c = Validators.composeAsync([asyncValidator("expected", {"one": true})]);
+
+           var value = null;
+           c(new Control("expected")).then(v => value = v);
+
+           tick(1);
+
+           expect(value).toEqual(null);
+         }));
+
+      it("should ignore nulls", fakeAsync(() => {
+           var c = Validators.composeAsync([asyncValidator("expected", {"one": true}), null]);
+
+           var value = null;
+           c(new Control("invalid")).then(v => value = v);
+
+           tick(1);
+
+           expect(value).toEqual({"one": true});
+         }));
+    });
   });
 }