Angularjs dynamic name of ng-model

Question

I'am using AngularJS and I use an ng-repeat block. I want to use a unique/dynamic ng-model name. The idea of this code is that when I click the buttom I increase the value of the textbox. The name of the parameters is correct in the debugger but the value is not changing. Below there is the code that I use but it is not working and I can not find why. Can anyone help me please?

<tr ng-repeat="item in resultShoppingCart track by $index">
   <td class="price" ng-bind="item.unitPrice"><span></span></td>
   <td class="qty">
      <input class="form-control input-sm" type="text" ng-value="item.quantity" ng-model="Qty['{{$index}}']">
      <a href=""><i class="fa fa-plus" ng-click="addQuantity(item.quantity, item.productId, $index)"></i></a> <a href="#"><i class="fa fa-minus"></i></a>
   </td>
   <td class="price" ng-bind="item.price"><span>$99.00</span></td>
   <td class="action"><a ng-click="delete(userId,item.productId)">Delete item</a></td>
</tr>

And my controller.

$scope.addQuantity = function (currentQuantity, productId, i) {          
          $scope["Qty['" + i + "']"] = currentQuantity + 1;
          alert($scope["Qty['" + i + "']"]);          
      }

Answer 1

Since the result of '{{$index}}' expression will be '{{$index}}' itself. So you have to change the expression to Qty[$index] rather than using Qty['{{$index}}'] inside ng-model, so that interpolation will evaluate it correctly.

---

But I would recommend to use item.quantity, which ultimately going to be unique itself. No need to maintain separate object (as such I don't see any reason save Quantity in separately).

<td class="qty">                            
    <input class="form-control input-sm" type="text" ng-value="item.quantity" ng-model="item.quantity" >
    <a href=""><i class="fa fa-plus" ng-click="addQuantity(item)"></i></a> <a href="#"><i class="fa fa-minus"></i></a>                            
</td>

Code

$scope.addQuantity = function (item) {          
    item.quantity = item.quantity + 1;
}