angularjs - Angular JS propagate child scope variable changes to parent scope

Question

How can I take variable changes and easily propagate them back to the ParentCtrl despite a 'new' var being instantiated in the ChildCtrl? Extra points for minimal to no $on's and $watch's (makes it easier to implement)

ParentCtrl

• ChildCtrl / ChildCtrl2 / ChildCtrl3 / ChildCtrl4

  • View

My ChildCtrl's are just different enough where I can't easily abstract a master layout and a ng-view, but they all depend on the same functions in ParentCtrl.

$scope.searchTerms is defined in ParentCtrl but the input box with ng-model='searchTerms' is in the view of the child controllers. When this var changes it's not reflected in the ParentCtrl only the ChildCtrls.

Example: http://jsfiddle.net/JHwxP/22/

HTML Partial

<div ng-app>
    <div ng-controller="Parent">
        parentX = {{x}} <br/>
        parentY = {{y}}<br/>
        <div ng-controller="Child">
            childX = {{x}}<br/>
            childY = {{y}}<br/>
            <a ng-click="modifyBothScopes()">modifyBothScopes</a><br>
            <br>
            The changes here need to appear in 'Parent'. <input ng-model='y'>
        </div>
    </div>
</div>

Controllers

function Parent($scope) {
    $scope.x= 5;
    $scope.y= 5;
}

function Child($scope) {
    $scope.modifyBothScopes= function() {
       $scope.$parent.x++;
    };  
}

UPDATE

I'm currently attempting a shared service approach: https://gist.github.com/exclsr/3595424

UPDATE

Trying an emit/broadcast system

SOLVED Problem: I was storing $scope.searchTerms in the parent and when changed created a space in the child $scope.

Solution: I should have done $scope.search.terms in the parent and when changed in the child it would bubble up to the parent.

Example: http://jsfiddle.net/JHwxP/23/

Answer 1

This is due to how prototypal inheritance works.

When you ask for $scope.x in the child controller, it checks to see if x is defined on its scope, and if not, looks for x in the parent scope.

If you assign to the child scope's x property, it only modifies the child scope.

An easy way to deal with this and get the sharing behavior is to use an object or an array.

function ParentCtrl($scope) {
  $scope.model = {x: 5, y: 5};
}

function ChildCtrl($scope) {
  $scope.update = function(x, y) {
    $scope.model.x = x;
    $scope.model.y = y;
  };
}

Here, the changes will be visible in both scopes, because $scope.model will refer to the same object in both parent and child scopes.

John Lindquist has a video on this.