Unable to pass controller and directive scope into child directive using require - angularjs

Question

I am trying to pass the controller scope of parent controller and parent directive into a child directive but facing an error saying that the controller is not available. Here is a plunk for that
http://plnkr.co/edit/aahgOK9oFFjcP2y5VkVa?p=preview
HTML:
<div ng-controller="MainCtrl as mc">
<new-dir>
<data-customer-details customer="mc.customers[0]" logger="mc.logger()" version-age="{{mc.age}}"></data-customer-details>
</new-dir>
</div>

Answer 1

OK, so I tinkered with your plunker a bit. I couldn't get it working using Controller As...I had to change it over to $scope injection on the main controller. Then I created a new scope on newDir by setting scope: true.
You don't actually need to require the MainCtrl because these directives are automatically children of that scope anyway.
I changed your 'MainCtrl' to this:
angular.module('plunker').controller('MainCtrl', function ($scope) {
$scope.name = 'World';
$scope.customers = [{
"name": "angularjs 1.4",
"version": "1.4"
}, {
"name": "angularjs 1.3",
"version": "1.3"
}, {
"name": "angularjs 1.2",
"version": "1.2"
}];
$scope.age = 30;
$scope.logger = function() {
console.log('clicked');
}
$scope.ctrlScopeVariable = 'im in controller scope';
})
Minor change to newDir:
function newDir (){
return {
scope: true, //you need this
controller: function($scope){
$scope.val= 'someval';
console.log($scope.$parent.ctrlScopeVariable)
},
link: function(scope, el, attr, ctrl) {
console.log(scope.$parent.name)
}
}
}
And the last directive:
function CustomerDetails() {
var directive = {
scope: {
customer: '=',
logger: '&',
myNewAge: '#versionAge'
},
restrict: 'EA',
require: ['^newDir'],
controllerAs: 'cd',
templateUrl: 'customer-details.html',
link: linkFunction,
controller: function($scope){
console.log($scope.$parent.$parent.ctrlScopeVariable);
var cd = this;
cd.newval = 'new val';
}
};
function linkFunction(scope, elem, attributes, controllers, transclude) {
console.dir(controllers);
scope.fromMainCtrl = scope.$parent.$parent.ctrlScopeVariable
}
return directive;
}
The Plunker
I added a binding to the customer details template that passes in the $scope.ctrlScopeVariable from the main controller, so you can see the MainCtrl scope is accessible form the child directive.
In regards to require, the relevant documentation is here, I think:
If it is necessary to reference the controller or any functions bound
to the controller's scope in the template, you can use the option
controllerAs to specify the name of the controller as an alias. The
directive needs to define a scope for this configuration to be used.
This is particularly useful in the case when the directive is used as
a component.
Looking back at myPane's definition, notice the last argument in its
link function: tabsCtrl. When a directive requires a controller, it
receives that controller as the fourth argument of its link function.
Taking advantage of this, myPane can call the addPane function of
myTabs.
Essentially, you can use it to reference a parent controller on which you need to access some functions or something. Notably, it becomes available under whatever alias you give it as the fourth argument of your link function.
EDIT:
In this Plunker I added a function to the controller of newDir, required newDir in the CustomerDetail directive, and then called that function in the CustomerDetail link function:
CustomerDetails directive:
//some stuff
require: '^newDir',
//some stuff
link: function(scope, el, attr, newDirCtrl) {
console.log(newDirCtrl.doubleNum(100));
}
newDir controller:
controller: function($scope){
this.doubleNum = function(num) {
return num*2
}
// some stuff
}

Answer 2

First you need to declare a variable as callback function:
var MainCtrlFn = function() { .... }
Then, you can set it as parameter to angularJS:
angular.module('plunker').controller('MainCtrl', MainCtrlFn);