angular set dirty form within directive controller - angularjs

Question

I have an angular driven form using $dirty to spot for changes to enable/disable submit button.
Part of the form uses a Directive for uploading a logo but the form is noticing this as a changed element so upon setting a logo that validates in size I need to manually trigger that the form has had a change so should be a case of formName.$setDirty(); however console is saying that $setDirty() is not defined and I think this is because I am within a directive.
Within my directives controller upon file selection I call the function below and it is here when the file is valid that I would want to call the setdirty method.
function isFileValid(file) {
vm.fileValid = true;
vm.errorMessage = "";
if (file.size > 16777216) {
vm.errorMessage = "The File is too big!";
vm.fileValid = false;
} else if (file.size == 0) {
vm.errorMessage = "The File is empty!";
vm.fileValid = false;
}
if (vm.fileValid) {
// make form dirty
$setDirty();
}
return vm.fileValid;
}
Here is the directive JS
(function () {
'use strict';
.module("tpBusinessProfile")
.directive("tpLogoUploader", tpLogoUploader);
function tpLogoUploader() {
return {
templateUrl: "tpLogoUploader.directive.html",
bindToController: true,
scope: {
changedMethod: "&"
},
controller: "tpLogoUploaderCtrl",
controllerAs: 'logoCtrl',
restrict: "E"
};
}
})();
Any help is appreciated.

Answer 1

You need to use directive require option and require controller of form directive:
{
require: '^form'
and then in link function bind method that you need to your scope (dirty solution):
link(scope, elem, attrs, formController){
scope.makeFormDirty = formController.$setDirty
}
and now you can use it in your controller via makeFormDirty