angularjs - How to pass dynamic values in "ng-if"?

Question

I have a problem with passing dynamic values in "ng-if". If I pass a static value then it's working, but when I pass dynamic values by concatenation of two variables it's not working. I tried with below code:

<ul class="list cart">
  <li class="cart_item"
      ng-repeat="product in orderInfo.products track by product.product_id"
      data-id="\{{product.product_id}}" id="items_list_{{product_id}}">
    <button
      ng-click="removeItem(product.product_id)"
      // If I pass a static value like "removed_31460" then its working.
      ng-if="removed_31460 == 'added'"
      // If tried to pass a dynamic value like below I am getting error as token not accepted.
      **ng-if="removed_+product.product_id == 'added'"**
      data-product-id="{{item_id}}"
      class="remove" data-id="\{{ product.product_id }}">
      Remove
    </button>
  </li>
</ul>

Note: "removed_31460" is defined in my app.js file.

Here is the runnable code:

function TodoCtrl($scope) {
    $scope.products = [
        {product_id:'123'},
        {product_id:'234'},
    ];
    let removed_id = '';
    for (let i = 0; i < $scope.products.length; i++) {
        removed_id = 'removed_'+ $scope.products[i].product_id;
        $scope[removed_id] = 'added';
    }
    $scope.removeItem = function(product_id) {
        alert('in ' + product_id);
    };
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/angular.js/1.0.3/angular.min.js"></script>
<div ng-app>
<div ng-controller="TodoCtrl">
<ul class="list cart">
  <li class="cart_item" ng-repeat="product in products" data-id="\{{product.product_id}}" id="items_list_{{product_id}}">
    <button
      ng-click="removeItem(product.product_id)"
      // If I pass a static value like "removed_31460" then its working.
      ng-if="removed_23445 == 'added'"
      // If tried to pass a dynamic value like below I am getting error as token not accepted.
      **ng-if="removed_+product.product_id == 'added'"**
      data-product-id="{{item_id}}"
      class="remove" data-id="\{{ product.product_id }}">
      Remove
    </button>
  </li>
</ul>
</div>
</div>

标签： angularjs

Answer 1

Use:

ng-if="this['removed_' + product.product_id] == 'added'"

The identifier this can be used to refer to $scope.

For more information, see

• AngularJS Developer Guide - Expression Context

---

The code can be changed to create a hash named statusById:

function TodoCtrl($scope) {
    $scope.products = [
        {product_id:'123'},
        {product_id:'234'},
    ];

    $scope.statusById = {};
    $scope.products.forEach(p => $scope.statusById[p.product_id] = 'added');

    $scope.removeItem = function(index) {
        $scope.products.splice(index,1);
        $scope.statusById[$scope.products[index].productId] = 'removed';
    };
}

Then the template can use $index:

<li ng-repeat="product in products" id="items_list_{{product_id}}">
    <button ng-click="removeItem($index)"
            ng-if="statusById[product.product_id] == 'added'"
    >
      Remove
    </button>
</li>

For more information, see

• AngularJS ng-repeat Directive API Reference - Overview