orderBy:random creates infdig errors

[mblase75]

Random orderBy sorting works smoothly in angular 1.1.1. It works in 1.2.x as well but generates infdig errors in the console.

http://jsfiddle.net/mblase75/jVs27/

JS:

var myApp = angular.module('myApp',[]);
function MyCtrl($scope) {
$scope.list = ['a', 'b', 'c', 'd', 'e', 'f', 'g'];
$scope.random = function() {
return 0.5 - Math.random();
}
}

error in console:

Error: [$rootScope:infdig] 10 $digest() iterations reached. Aborting!
Watchers fired in the last 5 iterations: [["fn: $watchCollectionWatch; newVal: 44; oldVal: 39"],["fn: $watchCollectionWatch; newVal: 49; oldVal: 44"],["fn: $watchCollectionWatch; newVal: 54; oldVal: 49"],["fn: $watchCollectionWatch; newVal: 61; oldVal: 54"],["fn: $watchCollectionWatch; newVal: 67; oldVal: 61"]]
http://errors.angularjs.org/1.2.11/$rootScope/infdig?p0=10&p1=%5B%5B%22fn%3…20%24watchCollectionWatch%3B%20newVal%3A%2067%3B%20oldVal%3A%2061%22%5D%5D
at https://ajax.googleapis.com/ajax/libs/angularjs/1.2.11/angular.js:78:12
at Scope.$digest (https://ajax.googleapis.com/ajax/libs/angularjs/1.2.11/angular.js:11853:19)
at Scope.$apply (https://ajax.googleapis.com/ajax/libs/angularjs/1.2.11/angular.js:12067:24)
at https://ajax.googleapis.com/ajax/libs/angularjs/1.2.11/angular.js:1302:15
at Object.invoke (https://ajax.googleapis.com/ajax/libs/angularjs/1.2.11/angular.js:3707:17)
at doBootstrap (https://ajax.googleapis.com/ajax/libs/angularjs/1.2.11/angular.js:1300:14)
at bootstrap (https://ajax.googleapis.com/ajax/libs/angularjs/1.2.11/angular.js:1314:12)
at angularInit (https://ajax.googleapis.com/ajax/libs/angularjs/1.2.11/angular.js:1263:5)
at https://ajax.googleapis.com/ajax/libs/angularjs/1.2.11/angular.js:20752:5
at HTMLDocument.trigger (https://ajax.googleapis.com/ajax/libs/angularjs/1.2.11/angular.js:2342:7)

[caitp]

You're going to have problems with this because of the instability of the model. You need to return the same array twice in a row to stop the digest from running again, and that's not going to happen like this.

[IgorMinar]

right, currently we assume that filters are idempotent (they have no state and return the same value given the same inputs).

I don't see this requirement going away until Angular 2.

To work around this, you could change your app to change the random coefficient outside of the filter function, that will prevent this issue.

[caitp]

Oops, did I forget to close this one again. My bad :(