Disabled my input submit after adding

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HTML5

AngularJs

MVC5

ASP.NET5

hello,

i want to disable my input submit for the first it works nice, i want to disable my input after adding same one this is my code it works fine

Html :

<form class="form-horizontal col-md-6" role="form" name="frm">





</form>
AngularJS:

app.controller('UserAdminAddController', function ($scope, httpService) {

$scope.Add = function () {
var data = {
firstname: $scope.firstname,
lastname: $scope.lastname
};
var log = httpService.request('api/User/AddUserByForm/', 'put', data);
log.then(function (result) {
if (result.data.Status == 'Succeed') {
$("input[name='Firstname']").val(null);
$("input[name='Lastname']").val(null);
$('#Succeed').fadeIn();
$('#Succeed').delay(3000).fadeOut(); }
else {

}

});
}
};
});

css:
input.ng-invalid.ng-dirty{border:1px solid red;}

What I have tried:

For the first time i have user ng-disabled="frm.$invalid" for my submit buton