Unable to invoke a custom directive inside another custom directive in AngularJs - html

Question

I want to invoke a custom directive inside another custom directive's template.
Please find below code snippets -
Scenario 1 (Not working)
angular.module('myApp')
.directive('customOnChange', function () {
return {
restrict: 'A',
link: function (scope, element, attrs) {
var onChangeFunc = scope.$eval(attrs.customOnChange);
element.bind('change', function (event) {
var files = event.target.files;
onChangeFunc(files);
});
element.bind('click', function () {
element.val('');
});
}
};
})
.directive('writePost', function () {
return {
restrict: 'E',
link: function (scope) {
scope.changeUserProfileImage = function (files) {
console.log(files); // I should receive uploaded files here.
};
},
templateUrl: function () {
return 'writePost.html';
}
};
});
index.html
<write-post></write-post>
writePost.html
<input type="file" ng-model="file" name="file"
id="photo-upload1" custom-on-change="changeUserProfileImage"
value="Change Image"
title="Change Image"/>
The error I am receiving when I upload a file -
Uncaught TypeError: onChangeFunc is not a function
Scenario 2 (Working)
Although independently I am able to call customOnChange directive from index.html. Working code snippet -
index.html
<input type="file" ng-model="file" name="file"
id="photo-upload1" custom-on-change="changeUserProfileImage"
value="Change Image"
title="Change Image"/>
myCtrl.js
angular.module('myApp')
.controller('myCtrl', ['$scope', function ($scope) {
$scope.changeUserProfileImage = function (files) {
console.log(files); // I am receiving uploaded files here.
};
}]);
Can someone help me identifying, where I am going wrong in first scenario ?

Answer 1

link in directive definition defaults to postLink - it executes after template with its directives is parsed. (read more here https://docs.angularjs.org/api/ng/service/$compile#pre-linking-function)
As a solution you can move $eval inside callback:
element.bind('change', function (event) {
var onChangeFunc = scope.$eval(attrs.customOnChange);
var files = event.target.files;
onChangeFunc(files);
});
Correct way:
If you want run function - let it be function in html:
custom-on-change="changeUserProfileImage(files)"
Now run it as function:
element.bind('change', function (event) {
var files = event.target.files;
scope.$eval(attrs.customOnChange, {files: event.target.files});
});