Angular, ng-messages not showing inside angular material design dialog (md-dialog)

Question

I'm working on a form to add a credit card in angularJS, with angular material (https://material.angularjs.org/latest/#/).

For all my other forms, i used ng-messages (https://docs.angularjs.org/api/ngMessages/directive/ngMessages) to show validation errors, and it worked fine.

When i embded the form inside a md-dialog, my ng-messages are not displaying, the input became invalid, but no error displayed. I've got the problem with basic validation directive and custom validation directive.

My dialog template :

<md-dialog>
<md-dialog-content style="max-width:800px;max-height:810px; ">
    <h2 i18n="add_card_button"></h2>
    <form name="form">
        <md-input-container>
            <label i18n="card_number"></label>
            <input  name="card_number"
                    type="text" 
                    ng-model="ctrl.newCard.cc_number"
                    class="md-input" 
                    required
                    card-number>
            <div ng-messages="form.card_number.$error">
                <div ng-message="cardNumber">test message</div>
                <div ng-message="required">test message 2</div>
            </div>
        </md-input-container>
        ...
    </form>
</md-dialog-content>
<div class="md-actions" layout="row">           
    <md-button ng-click="">
        <i18n>ok_button</i18n>
    </md-button>
    <md-button ng-click="cancel()" style="margin-right:20px;">
        <i18n>cancel_button</i18n>
    </md-button>
</div>

My dialog definition :

$mdDialog.show({
            controller : dialogController,
            controllerAs : "ctrl",
            bindToController : true,
            templateUrl : "creditCards/assets/templates/add_credit_card_dialog.html",
            parent : angular.element(document.body),
            targetEvent : event,
            clickOutsiteToClose : true,
            locals : {
                cardTypes : vm.cardTypes
            }
        });

and my custom directive definition

angular
    .module('app.core')
    .directive("cardNumber", cardNumber);

/* @ngInject */
function cardNumber () {
    var directive = {
        link: link,
        restrict: 'A',
        require : "ngModel"
    };
    return directive;

    function link(scope, element, attrs, ngModel) {
        ngModel.$validators.cardNumber = cardNumber;

        scope.$watch("cardNumber", function(){
            ngModel.$validate();
        });

        // Validate visa, mastercard, amex, concate new regex to validate more card
        var reg = new RegExp(/^(?:4[0-9]{12}(?:[0-9]{3})?|5[1-5][0-9]{14}|3[47][0-9]{13})$/);

        function cardNumber(modelValue){
            if(!modelValue){
                return true;
            }

            modelValue = modelValue
                            .replace(/-/g, "")
                            .replace(/\s/g, "")
                            .replace(/,/g, "");

            return reg.test(modelValue);
        }
    }
}

And a screenshot of the result where you can see the invalid field but no error message :

Answer 1

There are two possible fixes detailed here: https://github.com/angular/material/issues/8037

1. Make sure the ng-app directive is on the body tag of your page.

2. Remove the line parent: angular.element(document.body) from your $mdDialog.show() options.