angular.module('myApp', [])

.directive('ensureUnique', ['$http', function($http) {

  return {

    require: 'ngModel',

    link: function(scope, ele, attrs, c) {

      scope.$watch(attrs.ngModel, function() {

        $http({

          method: 'POST',

          url: '/api/check/' + attrs.ensureUnique,

          data: {'field': attrs.ensureUnique}

        }).success(function(data, status, headers, cfg) {

          c.$setValidity('unique', data.isUnique);

        }).error(function(data, status, headers, cfg) {

          c.$setValidity('unique', false);

        });

      });

    }

  };

}]);