ng-class condition changes, but not updating classes

Question

I have a very strange issue. I have to set an active class on the appropriate <li> when the $scope.selectedCat == cat.id. The list is generated with ng-repeat. If selectedCat is false, the 'Browse All Categories' list item (outside of ng-repeat) is set to active. setCat() sets the value of the $scope.selectedCat variable:

<div id="cat-list" ng-controller="CatController">
    <li ng-class="{'active': {{selectedCat == false}}}">
        <a>
            <div class="name" ng-click="setCat(false)" >Browse All Categories</div>
        </a>
    </li>
    <li class="has-subcat" ng-repeat="cat in cats | filter:catsearch" ng-class="{'active': {{selectedCat == cat.id}}}">
        <a>
            <div cat class="name" ng-click="setCat({{cat.id}})" ng-bind-html="cat.name | highlight:catsearch"></div>
        </a>
    </li>
</div>

When the page loads, everything works fine (snapshot from FireBug):

<li ng-class="{'active': true}" class="ng-scope active">
<!-- ngRepeat: cat in cats | filter:catsearch -->
<li class="has-subcat ng-isolate-scope" ng-repeat="cat in cats | filter:catsearch" ng-class="{'active': false}">

However when I set $scope.selectedClass to a cat.id value, the condition within ng-class gets evaluated correctly, but ng-class won't update the classes accordingly:

<li ng-class="{'active': false}" class="ng-scope active"> <!--Right here!-->
<!-- ngRepeat: cat in cats | filter:catsearch -->
<li class="has-subcat ng-isolate-scope" ng-repeat="cat in cats | filter:catsearch" ng-class="{'active': true}">

Please note that in the first line active class stays set, while ng-class evaluates to false. In the last line active is not set, while ng-class evaluates to true.

Any ideas why it doesn't work? What's the correct Angular way of doing this?

Answer 1

Replace:

ng-class="{'active': {{selectedCat == cat.id}}}"

With:

ng-class="{'active': selectedCat == cat.id}"

You never need to nest those curly braces like that, in Angular.

Have a look at the ng-class documentation for some more examples.

Answer 2

Instead of

ng-class="{'active': {{selectedCat == cat.id}}}"

use

ng-class="{active: selectedCat == cat.id}"

Answer 3

Hi i'm also facing the same problem. i solved the problem by the way instead of assigning the value directly to ng-class, call the separate method and return the value.

ex :

ng-class="getStyleClass(cat)"

$scope.getStyleClass = function(cat)  {   
      return "active: selectedCat == cat.id";  
}

roughly i coded. please change the method as per your requirement.