AngularJS [$rootScope:infdig] error with Random Number function - angularjs

Question

I am getting a [$rootScope:infdig] error but my code actually works. What I am trying to do is load an image or a random placeholder image if one does not exist.
<div ng-repeat="v in tiles track by $index" id="text-{{v.ID}}" class="lity-hide row-fluid lityBox">
<div class="span3">
<img ng-src="{{v.Image !== undefined ? v.Image.split(',')[0] : getPlaceholderImg() }}">
<h4 class="centerMe">{{v.Title}}</h4>
</div>
</div>
Here is the function in $scope:
$scope.getPlaceholderImg = function() {
$scope.placeholderImg = "http://myurl.com/defaultImg" + Math.floor((Math.random()*5)+1) + ".jpg";
return $scope.placeholderImg;
}

Answer 1

One solution is to use the one-time binding operator (::) to stabilize the expression:
<div ng-repeat="v in tiles track by $index" id="text-{{v.ID}}" class="lity-hide row-fluid lityBox">
<div class="span3">
̶<̶i̶m̶g̶ ̶n̶g̶-̶s̶r̶c̶=̶"̶{̶{̶v̶.̶I̶m̶a̶g̶e̶ ̶!̶=̶=̶ ̶u̶n̶d̶e̶f̶i̶n̶e̶d̶ ̶?̶ ̶v̶.̶I̶m̶a̶g̶e̶.̶s̶p̶l̶i̶t̶(̶'̶,̶'̶)̶[̶0̶]̶ ̶:̶ ̶g̶e̶t̶P̶l̶a̶c̶e̶h̶o̶l̶d̶e̶r̶I̶m̶g̶(̶)̶ ̶}̶}̶"̶>̶
<img ng-src="{{::v.Image !== undefined ? v.Image.split(',')[0] : getPlaceholderImg() }}">
<h4 class="centerMe">{{v.Title}}</h4>
</div>
</div>
For more information, see
AngularJS Developer Guide - One-Time Binding
AngularJS Error Reference - $rootScope:infdig
Infinite $digest Loop.