Trigger validation of a field when another field is changed

Question

I have a custom validation directive that is being called properly when one field is changed. However, whether this field is valid is also based on another field's value. This second field is a select list if that is of importance.

I was wondering if there was some way I could trigger validation manually when the second form is changed. Perhaps by using the ng-change event. What is the proper way to handle something like this?

Here is my directive:

angular.module('myApp', []).     directive('validage', function () {         return {             require: 'ngModel',             link: function (scope, elem, attr, ngModel) {                  function validate(value) {                     var valid = true;                     if ((GetDateDifference(new Date(value), new Date()) < 16 || GetDateDifference(new Date(value), new Date()) > 129)                     && scope.dep.DependantType == "Spouse") {                         valid = false;                     }                     ngModel.$setValidity('validage', valid);                     return value;                 }                  //For DOM -> model validation                 ngModel.$parsers.unshift(function (value) {                     var valid = true;                     if ((GetDateDifference(new Date(value), new Date()) < 16 || GetDateDifference(new Date(value), new Date()) > 129)                     && scope.dep.DependantType == "Spouse") {                         valid = false;                     }                     ngModel.$setValidity('validage', valid);                     return value;                 });                  //For model -> DOM validation                 ngModel.$formatters.unshift(function (value) {                     var valid = true;                     if ((GetDateDifference(new Date(value), new Date()) < 16 || GetDateDifference(new Date(value), new Date()) > 129)                     && scope.dep.DependantType == "Spouse") {                         valid = false;                     }                     ngModel.$setValidity('validage', valid);                     return value;                 });             }         };     }); 

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Answer 1

After searching a lot for this I've found that we can trigger validation simply by calling $validate() on the desired field.
So for example if your form is named my_form (i.e. in the markup the form tag has a name="my_form" attribute) and the name of the field you want to validate is date (in the markup the input field has a name="date" attribute), then as you suggested you can use the ng-change event of the second field and call $scope.my_form.date.$validate(); whenever the ng-change function is invoked.