angularjs: custom directive to check if a username exists - angularjs

Question

I have my registration form with textbox username. I want to do is when the user enter the username, the custom directive will check if the entered username is exists in the database.
directives.js
angular.module('installApp').directive('pwCheck', function ($http) {
return {
require: 'ngModel',
link: function (scope, elem, attrs, ctrl) {
elem.on('blur', function (evt) {
scope.$apply(function () {
$http({
method: 'GET',
url: '../api/v1/users',
data: {
username:elem.val(),
dbField:attrs.ngUnique
}
}).success(function(data, status, headers, config) {
ctrl.$setValidity('unique', data.status);
});
});
});
}
}
});
If it's exists, my div class = "invalid" will shown in the html form with label "Username already exists."
registration.html
<form name = "signupform">
<label>{{label.username}}</label>
<input type="text" id = "username" name = "username" ng-model="user.username" class="form-control"></input>
<div class="invalid" ng-show="signupform.username.$dirty && signupform.username.$invalid"><span ng-show="signupform.username.$error.unique">Username already exists.</span>
</div>
</form>
But right now, they are not working :-(,am I doing right? Please advice or suggest me things I should do. Thanks in advance.

Answer 1

there is a great tutorial by yearofmoo about $asyncvalidators in angular1.3. it allows you to easily show pending status when the field is being checked by the backend:
here's a working plnkr
app.directive('usernameAvailable', function($timeout, $q) {
return {
restrict: 'AE',
require: 'ngModel',
link: function(scope, elm, attr, model) {
model.$asyncValidators.usernameExists = function() {
//here you should access the backend, to check if username exists
//and return a promise
//here we're using $q and $timeout to mimic a backend call
//that will resolve after 1 sec
var defer = $q.defer();
$timeout(function(){
model.$setValidity('usernameExists', false);
defer.resolve;
}, 1000);
return defer.promise;
};
}
}
});
html:
<form name="myForm">
<input type="text"
name="username"
ng-model="username"
username-available
required
ng-model-options="{ updateOn: 'blur' }">
<div ng-if="myForm.$pending.usernameExists">checking....</div>
<div ng-if="myForm.$error.usernameExists">username exists already</div>
</form>
note the use of ng-model-options, another cool feature of 1.3
edit
here's a plnkr that shows how to use $http in the directive. note that it is only requesting another .json file, that contains a true/false value. and the directive will set validity on the ng-model accordingly.