javascript - Validate angular form programmatically -

i have angular directive used attribute validating input.

input looks (jade)

 input.form-control(type='text',  name='subjectinput', id='subjectinput',  subjectid-noprefix-validator='(subject.nosuffix==1)') 

and validator looks

.directive('subjectidnoprefixvalidator', function () {          return {         require: ['^form', 'ngmodel'],         scope: {             noprefixformat: '=subjectidnoprefixvalidator'         },         link: function (scope, element, attrs, ctrls) {              scope.form = ctrls[0]; // can use form reference in displaying error messages             var ngmodel = ctrls[1];             ngmodel.$validators.subjectidnoprefix = function (value) {                  var status = true;                 // removed logic sets status true or false                 // using   $scope.noprefixformat parameter                 return status;             };         }     }; }); 

it works fine. however, in page actions event happens need validation re-triggered on input without touching it; radio button alteration should re-trigger , refresh validation status (as see, validator has parameter).

i tried achieve calling in page controller

 $scope.subjcreationform.subjectinput.$validate();  

but not seem work. case , there way trigger validation of field programmatically when employs $validators?

found core of problem, $apply has called manually can achieved such:

           $timeout(function () {                     $scope.subjcreationform.subjectinput.$validate();                 });