<div class="form-group" ng-class="{'has-error': myForm.myName.$touched && myForm.myName.$invalid}">
  <label class="col-xs-2 control-label">name</label>
  <div class="col-xs-6">
    <input type="text" class="form-control" name="myName" ng-model="formData.username"
        placeholder="2-10个中英文字符，aaa会重名，必填"
        name-check minlength="2" maxlength="10" required>
  </div>
  <div class="col-xs-4 form-control-static text-danger" ng-messages="myForm.myName.$error"
           ng-messages-include="demos/form/error.html" ng-show="myForm.myName.$touched">
  </div>
</div>

<span ng-message="required">必填</span>
<span ng-message="char">非法字符</span>
<span ng-message="exist">名称已存在</span>
<span ng-message="minlength">太短了</span>

app.directive('nameCheck', nameCheck);

nameCheck.$inject = ['HttpService', '$q'];

function nameCheck(HttpService, $q){

  var NAME_REG = /^[a-zA-Z\u4e00-\u9fa5]+$/;

  return {
    restrict: 'A',
    require: 'ngModel',
    link:function($scope,element,attrs,ctrl){

      ctrl.$validators.char = function(modelValue, viewValue) {
        var value = modelValue || viewValue;
        if(!NAME_REG.test(value)){
          return false;
        }
        return true;
      };
      ctrl.$asyncValidators.exist = function(modelValue, viewValue){
        var value = modelValue || viewValue;
        var deferred = $q.defer();
        HttpService.get('api/users/' + value).then(function(res) {
          if(res.isExist){
            deferred.reject(false);

          }
          deferred.resolve(true);
        })

        return deferred.promise;
      }
    }
  }
}