This is a angularjs directive for ensuring unique feilds in form

angular.js

app.directive('ensureUnique', ['$http', function ($http) {
    return {
        require: 'ngModel',
        link: function (scope, ele, attrs, c) {

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

                if(scope[attrs.ngModel] !== undefined) {
                $http({
                    method: 'POST',
                    url: '/' + attrs.ensureUnique,
                    data: {'field': scope[attrs.ngModel] }
                }).success(function (data, status, headers, cfg) {


                    c.$setValidity('unique', data[0].isUnique);
                    }).error(function (data, status, headers, cfg) {
                        c.$setValidity('unique', false);
                    });

                }
            });
        }
    }
}]);

serverCode.js

 app.post('/checkMobile', auth.confirmUser, function (req, res) {
        if (req.body.field !== undefined) {
            var mobile = req.body.field;
            var query = 'SELECT * FROM `users` WHERE  `email` LIKE "' + email + '"';
            utils.exec(query, {}, function (err, result) {
                if (!result.length) {
                    res.json([
                        {isUnique: true}
                    ]);
                } else {
                    res.json([
                        {isUnique: false}
                    ]);
                }
            })
        } else {
            res.json([
                {isUnique: false}
            ]);
        }
    });