Error: [ngRepeat:dupes] what does this mean?

Question

repeat directive outputing wine records from an api. I have a factory function to serve up the wine API which is then accessed in my controller

app.factory("Wine", function ($http){      var factory = {};       //getWines       factory.getWines = function(){        return $http.get("http://www.greatwines.9000.com")      }  } 

Controller:

    app.controller("winesCtrl", function($scope, $http, Wine){         Wine.getWines()          .success(function(wines){            $scope.wines = wines;         })         .error(function(){              alert("Error!");          });     });  VIEW:  <h2>Wine list</h2>     <div class="row margin-top-20 wine-container" ng-repeat="wine in wines">         <div class="col-sm-3">             <img src="{{wine.picture}}" class="img-responsive" />         </div>         <div class="col-sm-9">             <div class="margin-top-20">                 <span class="bold">Name: </span><span>{{wine.name}}</span>             </div>             <div>                 <span class="bold">Year: </span><span>{{wine.year}}</span>             </div>             <div>                 <span class="bold">Grapes: </span><span>{{wine.grapes}}</span>             </div>             <div>                 <span class="bold">Country: </span><span>{{wine.country}}</span>             </div>             <div>                 <span class="bold">Region: </span><span>{{wine.region}}</span>             </div>             <div>                 <span class="bold">Price: </span><span>{{wine.price}}</span>             </div>             <div>                 <span class="bold">{{wine.description}}</span>             </div>             <div class="margin-top-20">                 <a href="#/wines/{{wine.id}}" class="btn btn-default">Edit Wine</a>             </div>         </div>     </div> 

I clicked on this error and in typical "vague" angularjs fashion I get this:

Duplicates in a repeater are not allowed. Use 'track by' expression to specify unique keys. Repeater: wine in wines, Duplicate key: string:e, Duplicate value: e 

What does this mean? wine is not the same as "wines" so why does it think it is a duplicate?

Answer 1

Occurs if there are duplicate keys in an ngRepeat expression. Duplicate keys are banned because AngularJS uses keys to associate DOM nodes with items.

This means that $scope.wines have some values which are duplicate.

You can also refer this post : Angular ng-repeat Error "Duplicates in a repeater are not allowed."

Answer 2

It is true that AngularJS uses keys to associate DOM nodes with items. So, you can solve by adding "track by $index".

It will look like this

ng-repeat="wine in wines track by $index"