angular ng-repeat expressions as variables

Question

I'm trying to do something like this:

<ul>
    <li ng-repeat="{{myRepeatExpression}}">{{row.name}}</li>
</ul>

But because the ng-repeat logic is in the compile state of the directive it treats the {{myRepeatExpression}} as a normal string instead of a variable. Which doesn't work, obviously.

Is there any workaround for that?

Answer 1

You can only use and expression with ng-repeat and not an interpolated value. Now in order to create a dynamic repeatable list you can try either:

1. using a function that returns the list dynamically in the ng-repeat - this is potentially more expensive since angular needs to call the function first then determine if the collection has changed when doing a $digest cycle
2. $watch for a particular variable on the scope that trigger a change of the list - potentially more efficient but if your dynamic list depends on more than one variable it can get more verbose and can lead to potential bugs from forgetting to add a new $watch when a new variable is required

Demo plunker

JS:

app.controller('MainCtrl', function($scope) {
  var values1 = [{name:'First'}, {name:'Second'}];
  var values2 = [{name:'Third'}, {name:'Fourth'}, {name:'Fifth'}];

  //1. function way
  $scope.getValues = function(id) {
    if(id === 1) {
      return values1;
    }
    if(id === 2) {
      return values2;
    }
  }

  //2. watch way
  $scope.values = undefined;
  $scope.$watch('id', function(newVal) {
    $scope.values = $scope.getValues(newVal);
  });
});

HTML:

<!-- Here we pass the required value directly to the function -->
<!-- this is not mandatory as you can use other scope variables and/or private variables -->
<ul>
  <li ng-repeat="v in getValues(id)">{{v.name}}</li>
</ul>
<!-- Nothing special here, plain old ng-repeat -->
<ul>
  <li ng-repeat="v in values">{{v.name}}</li>
</ul>