add new angularJs event to a button on input value change using controller in angularJs - angularjs

Question

I m trying to add angularJs event to a button if value of input field changes. But i cannot find a solution how can i do it. I know how to detect change but do not know how to add a new event using controller.
Let me illustrate by example:
<form name="addNewCourse">
<input ng-model="courseNameEdit" ng-value="courseName" ng-pattern="regex" ng-trim="false" name="addNewCourseField" ng-minlength="5" ng-maxlength="60" required>
<div ng-messages="addNewCourse.addNewCourseField.$error" style="text-align: left !important; color:red;">
<div ng-message="required">This field is required*</div>
<div ng-message="pattern">Must be only digits or numbers</div>
<div ng-message="maxlength">Must not exceed 60 characters</div>
<div ng-message="minlength">Must not be smaller than 5 characters</div>
</div>
<button class="btn btn-primary" ng-click="saveCourseNameFunc(courseNameEdit)">Save</button>
</form>
what i want is to add ng-disabled="addNewCourse.$invalid" into the button if value change using controller. Thanks in Advance.

Answer 1

If I'm not wrong here, You are about to validate your form while field value changes via the controller. Try below solution and let me know if this will not work for you.
FORMOBJECT.$setSubmitted();
You can also try triggering change event of that field via controller like:
angular.element('#INPUT_ID').trigger('change');
Hope you will get the solution from one of the given above.

Answer 2

How about using ng-change and a boolean in your ng-disabled expression activate the disability simply.
<form name="addNewCourse">
<input ng-change="changed()" ng-disabled="addNewCourse.$invalid && activeDisable" ng-model="courseNameEdit" ng-value="courseName" ng-pattern="regex" ng-trim="false" name="addNewCourseField" ng-minlength="5" ng-maxlength="60" required>
<div ng-messages="addNewCourse.addNewCourseField.$error" style="text-align: left !important; color:red;">
<div ng-message="required">This field is required*</div>
<div ng-message="pattern">Must be only digits or numbers</div>
<div ng-message="maxlength">Must not exceed 60 characters</div>
<div ng-message="minlength">Must not be smaller than 5 characters</div>
</div>
<button class="btn btn-primary" ng-click="saveCourseNameFunc(courseNameEdit)">Save</button>
</form>
and your controller must contain something like this:
$scope.activeDisable = false;
$scope.change = function(){
$scope.activeDisable = true;
}