show validation error messages on submit in angularjs

Since I'm using Bootstrap 3, I use a directive: (see plunkr)

    var ValidSubmit = ['$parse', function ($parse) {
        return {
            compile: function compile(tElement, tAttrs, transclude) {
                return {
                    post: function postLink(scope, element, iAttrs, controller) {
                        var form = element.controller('form');
                        form.$submitted = false;
                        var fn = $parse(iAttrs.validSubmit);
                        element.on('submit', function(event) {
                            scope.$apply(function() {
                                element.addClass('ng-submitted');
                                form.$submitted = true;
                                if(form.$valid) {
                                    fn(scope, {$event:event});
                                }
                            });
                        });
                        scope.$watch(function() { return form.$valid}, function(isValid) {
                            if(form.$submitted == false) return;
                            if(isValid) {
                                element.removeClass('has-error').addClass('has-success');
                            } else {
                                element.removeClass('has-success');
                                element.addClass('has-error');
                            }
                        });
                    }
                }
            }
        }
    }]

    app.directive('validSubmit', ValidSubmit);

and then in my HTML:

<form class="form-horizontal" role="form" name="form" novalidate valid-submit="connect()">
  <div class="form-group">
    <div class="input-group col col-sm-11 col-sm-offset-1">
      <span class="input-group-addon input-large"><i class="glyphicon glyphicon-envelope"></i></span>
      <input class="input-large form-control" type="email" id="email" placeholder="Email" name="email" ng-model="email" required="required">
    </div>
    <p class="col-sm-offset-3 help-block error" ng-show="form.$submitted && form.email.$error.required">please enter your email</p>
    <p class="col-sm-offset-3 help-block error" ng-show="form.$submitted && form.email.$error.email">please enter a valid email</p>
  </div>
</form>

UPDATED

In my latest project, I use Ionic so I have the following, which automatically puts .valid or .invalid on the input-item's:

.directive('input', ['$timeout', function ($timeout) {
  function findParent(element, selector) {
    selector = selector || 'item';
    var parent = element.parent();
    while (parent && parent.length) {
      parent = angular.element(parent);
      if (parent.hasClass(selector)) {
        break;
      }
      parent = parent && parent.parent && parent.parent();
    }
    return parent;
  }

  return {
    restrict: 'E',
    require: ['?^ngModel', '^form'],
    priority: 1,
    link: function (scope, element, attrs, ctrls) {
      var ngModelCtrl = ctrls[0];
      var form = ctrls[1];

      if (!ngModelCtrl || form.$name !== 'form' || attrs.type === 'radio' || attrs.type === 'checkbox') {
        return;
      }

      function setValidClass() {
        var parent = findParent(element);
        if (parent && parent.toggleClass) {
          parent.addClass('validated');
          parent.toggleClass('valid', ngModelCtrl.$valid && (ngModelCtrl.$dirty || form.$submitted));
          parent.toggleClass('invalid', ngModelCtrl.$invalid && (ngModelCtrl.$dirty || form.$submitted));
          $timeout(angular.noop);
        }
      }

      scope.$watch(function () {
        return form.$submitted;
      }, function (b, a) {
        setValidClass();
      });


      var before = void 0;
      var update = function () {
        before = element.val().trim();
        ngModelCtrl.$setViewValue(before);
        ngModelCtrl.$render();
        setValidClass();
      };
      element
        .on('focus', function (e) {
          if (ngModelCtrl.$pristine) {
            element.removeClass('$blurred');
          }

        })
        .on('blur', function (e) {
          if (ngModelCtrl.$dirty) {
            setValidClass();
            element.addClass('$blurred');
          }
        }).on('change', function (e) {
          if (form.$submitted || element.hasClass('$blurred')) {
            setValidClass();
          }
        }).on('paste', function (e) {
          if (form.$submitted || element.hasClass('$blurred')) {
            setValidClass();
          }
        })
      ;

    }
  };
}])

and then in the HTML:

    <form name='form' novalidate="novalidate" ng-submit="auth.signin(form, vm)">
          <label class="item item-input item-floating-label">
            <span class="input-label">Email</span>
            <input type="email" placeholder="Email" ng-model="vm.email" autofocus="true" required
              >
          </label>
          <button ng-if="!posting" type="submit" class="item button-block item-balanced item-icon-right  call-to-action">Login<i class="icon ion-chevron-right"></i>
          </button>

and in the controller:

  self.signin = function (form, data) {
    if (!form.$valid) return;

    Authentication.emailLogin(data)
    //...

so, now, in the CSS, you can do stuff like:

.item.valid::before{
    float: right;
    font-family: "Ionicons";
    font-style: normal;
    font-weight: normal;
    font-variant: normal;
    text-transform: none;
    text-rendering: auto;
    line-height: 1;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    color: #66cc33;
    margin-right: 8px;
    font-size: 24px;
    content: "\f122";
}

.item.invalid::before{
    float: right;
    font-family: "Ionicons";
    font-style: normal;
    font-weight: normal;
    font-variant: normal;
    text-transform: none;
    text-rendering: auto;
    line-height: 1;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    color: #ef4e3a;
    margin-right: 8px;
    font-size: 24px;
    content: "\f12a";

/*
    border-left: solid 2px #ef4e3a !important;
    border-right: solid 2px #ef4e3a !important;
*/
}

MUCH SIMPLER!


I found this fiddle http://jsfiddle.net/thomporter/ANxmv/2/ which does a nifty trick to cause control validation.

Basically it declares a scope member submitted and sets it true when you click submit. The model error binding use this extra expression to show the error message like

submitted && form.email.$error.required

UPDATE

As pointed out in @Hafez's comment (give him some upvotes!), the Angular 1.3+ solution is simply:

form.$submitted && form.email.$error.required

I also had the same issue, I solved the problem by adding a ng-submit which sets the variable submitted to true.

<form name="form" ng-submit="submitted = true" novalidate>
<div>
    <span ng-if="submitted && form.email.$error.email">invalid email address</span> 
    <span ng-if="submitted && form.email.$error.required">required</span>
    <label>email</label>
    <input type="email" name="email" ng-model="user.email" required>
</div>

<div>
    <span ng-if="submitted && form.name.$error.required">required</span>
    <label>name</label>
    <input type="text" name="name" ng-model="user.name" required>
</div>

<button ng-click="form.$valid && save(user)">Save</button>
</form>

I like the idea of using $submitted, I think I've to upgrade Angular to 1.3 ;)