ng-model not updating when value changes

Question

Currently I have two date inputs. I am trying to make the second date input default to the first date input. The user can then change the second date input to be a different value (leaving the first unchanged).

The second date input is updating fine when I change my first date, however, the ng-model isn't modelling the value change to the form_data.to_date attribute and so this is resulting in the form still being invalid even though both required fields have been filled out.

Here is an example of the issue:

 angular.module('myApp', []) .controller('myController', function($scope) { $scope.form_data = { from_date: '', to_date: '' }; $scope.f = function() { setTimeout(function() { // delay to show that to_date is not updating console.log($scope.form_data); }, 1000); } }); angular.element(document).ready(() => {angular.bootstrap(document, ['myApp']);});

 <script src="https://cdnjs.cloudflare.com/ajax/libs/angular.js/1.7.5/angular.min.js"></script> <div ng-controller="myController"> <form name="myForm"> <input type="date" ng-model="form_data.from_date" name="from_date" ng-change="f()" required /> <input type="date" ng-model="form_data.to_date" name="to_date" ng-value="form_data.to_date || form_data.from_date | date: 'yyyy-MM-dd'" required /> <p>Form invalid: {{myForm.$invalid}}</p> <!-- Should be false when first date is changed --> </form> </div>

How can I get the ng-model on the second date input to model its changes when the value is changed in the first input?

Answer 1

This is because you are using ng-value="form_data.to_date || form_data.from_date | date: 'yyyy-MM-dd'" ie if form_data.to_date exists then assign it, if not then assign form_data.from_date but it won't update the value of ng-model .

To do this you can modify your code like this:

 angular.module('myApp', []) .controller('myController', function ($scope) { $scope.form_data = { from_date: '', to_date: '' }; $scope.f = function () { setTimeout(function () { // delay to show that to_date is not updating if ($scope.form_data.to_date == "") { $scope.form_data.to_date = $scope.form_data.from_date; } console.log($scope.form_data); $scope.$apply(); }) } }); angular.element(document).ready(() => { angular.bootstrap(document, ['myApp']); });

 <script src="https://cdnjs.cloudflare.com/ajax/libs/angular.js/1.7.5/angular.min.js"></script> <div ng-controller="myController"> <form name="myForm"> <input type="date" ng-model="form_data.from_date" name="from_date" ng-change="f()" required /> <input type="date" ng-model="form_data.to_date" name="to_date" ng-value="form_data.from_date | date: 'yyyy-MM-dd'" required /> <p>Form invalid: {{myForm.$invalid}}</p> <!-- Should be false when first date is changed --> </form> </div>