Exposing directive controller to parent controller - angularjs

Question

I want to expose some of my directive's functionality through its controller (think a public API for this directive).
return {
restrict: 'E',
scope: {},
controller: function($scope) {
this.method1 = ...;
this.method2 = ...;
},
controllerAs: 'dir',
link: function (scope, element, attrs) { ... }
}
Then in my parent controller or template call dir.method1 to get stuff accomplished inside the directive. Any ideas if this is possible as of Angular 1.3?
I'd like to refrain from event passing or even function passing, I have heard this is possible although I have never seen an implementation of this.

Answer 1

It is possible, but your issue isn't to figure out how to get the API out. It's how to get TO it from the parent. You're creating an isolate scope through your use of the 'scope' option. You're also making an element-type directive, so I'm guessing you're doing something like this:
<my-parent>
<my-child></my-child>
</my-parent>
where <my-parent> is the parent directive, and <my-child> is the directive with the API you want to expose.
The real question is what you're trying to achieve here. There is totally a way to do what you're asking. Just because the scope is isolated doesn't mean you can't get to it. You can just iterate through the parent $scope's $$childHead/etc list to find the child whose API you want to access. Anything you define in the child like this:
$scope.myApiFunction = function() {
};
will be visible here. (Things you put into 'this' will not - use the $scope storage bucket instead.)
That means if you only had ONE child you could do something like this from the parent controller:
$scope.$$childHead.myApiFunction();
Simple. Also, very crude. There are lots of problems here: what if you have many children? What if this child with its API ends up one level down? Etc. It's breaking all kinds of OO patterns and it's going to get messy, fast.
Your question is very abstract - it might be good if you updated it with an exact example. Without that, let me guess at your goal. There are two ways to do something "like this" that are encouraged within Angular:
Services. Whenever you say "API", think Service first. A service is a singleton (automatically) so it's tailor-made for creating APIs. And services can use the Factory pattern to return objects of a type, so THOSE are tailor made for doing things like having a manager service handle, say, a buddy list in an IM client, with API methods for creating, removing, and finding buddies.
Items that add "optional" functionality to their parents when they're defined. Let's say we have three possible types of tooltips: tooltips that have a hover effect, those that have a click effect, and those that are triggered by a "walkthrough" system in some order. For this kind of thing, the easy thing to do is just reverse the API, like this:
Parent Controller:
$scope.tooltipHandler = {
showTooltip: function() {},
hideTooltip: function() {}
};
Child Controller:
$scope.$parent.tooltipHandler = {
showTooltip: function() {
// Do some real work
},
hideTooltip: function() {
// Do some real work
},
}
What happens here is if there's no tooltip defined, when the parent runs its walkthrough, nothing happens. If you add the blue tooltip display module, when the parent runs its walkthrough now, it's going to show blue tooltips.
Make sense?

Answer 2

I arrived here looking for a similar response. So far the best that I can figure is to do what Angular does with ngForm.
In the documentation clearly states
If the name attribute is specified, the form controller is published onto the current scope under this name.
This basically makes the form controller accessible from anywhere.
If you have the following DOM
<div ng-controller="MyCtrl as parentCtrl">
<form name="parentCtrl.frmCtrl">
<my-child-directive>
</form>
</div>
You can use require: 'ngForm' in my-child-directive to get access from an inside directive. If you are in the parent controller you can access it trough the frmCtrl variable.
Not sure if this is best practice. In ngForm the name attribute works well, but I don't even know how to call such an attribute for a custom directive.
Thats why I arrived here, I wanted to know if this is "The Angular way" and what types of convetions are on the subject.
Hope it helps!