Using ng-if outside of ng-repeat can cause issues with ng-repeat loops in AngularJS

Question

Using ng-if outside of ng-repeat can cause issues with ng-repeat loops in AngularJS

AngularJS Version: 1.3.8

JSFiddle Link: http://jsfiddle.net/uYFE9/4/

I've been working on a small AngularJS project and encountered an issue. I have implemented an ng-repeat in a form that gets populated based on the selection from a dropdown menu linked to a model using ng-options. Here is a snippet of the code:

<select id="testAmount" ng-model="selectedItem" ng-options="item.name for item in items"></select>

<form role="form" name="testForm" ng-if="!complete">
    <div ng-repeat="i in getNumber(selectedItem.number) track by $index">
        {{$index}}
    </div>
</form>

Initially, the variable complete is set to false. Clicking a Next button will toggle the value of

complete</code, hiding the form and dropdown. Pressing the <code>Back

button will then revert the value of

complete</code back, displaying the form again.</p>

<p>The issue arises with the use of <code>ng-if

on the select element (and previously, when I had the form enclosed in a div with the same ng-if). The ng-repeat stops updating when the selection in the dropdown changes. However, removing the ng-if from the select restores the functionality of ng-repeat.

I am unsure if there is a problem with the nesting structure or if it is a bug within AngularJS itself. Feel free to test it out on the provided JSFiddle link. The $index should be printed as many times as the selected number in the dropdown, but it does not display correctly.

An interesting observation is that when I debugged this issue on my local setup, having FireBug open seemed to resolve the problem.

javascript angularjs angularjs-ng-repeat

Answer 1

Answer №1

The reason behind this issue is related to the ng-if directive creating a separate child scope and how primitive prototypical inheritance interacts with it. Specifically, when you set the value of selectedItem through the <select> element, it is actually assigned to the child scope, which then conceals or overrides the parent scope's property.

It is advisable to always incorporate a dot (.) notation in your ng-models:

$scope.selection = {selectedItem: undefined};

And in your HTML template:

<div ng-if="!complete">
  <select ng-model="selection.selectedItem" 
          ng-options="item.name for item in items"></select>
</div>

Answer 2

The reason behind this issue is related to the ng-if directive creating a separate child scope and how primitive prototypical inheritance interacts with it. Specifically, when you set the value of selectedItem through the <select> element, it is actually assigned to the child scope, which then conceals or overrides the parent scope's property.

It is advisable to always incorporate a dot (.) notation in your ng-models:

$scope.selection = {selectedItem: undefined};

And in your HTML template:

<div ng-if="!complete">
  <select ng-model="selection.selectedItem" 
          ng-options="item.name for item in items"></select>
</div>

Answer 3

Answer №2

ng-if is causing scoping complications that are interfering with the binding process.

For a workaround, you can refer to this updated jsfiddle example. In this solution, another div is wrapped around the elements that need to be hidden. Additionally, a next function is included to ensure that the scope remains consistent when the click event occurs and sets complete to true.

HTML:

<div ng-app="test">
    <div ng-controller="TestCtrl">
        <div ng-if="!complete">
            <div>
                <label for="testAmount">Amount:</label>
                <select id="testAmount" ng-model="selectedItem" ng-options="item.name for item in items"></select>
            </div>

            <form role="form" name="testForm">
                <div ng-repeat="i in getNumber(selectedItem.number) track by $index">
                    {{$index + 'hi'}}
                </div>
                <button class="btn btn-default" value="Next" title="Next" ng-click="next()">Next</button>
            </form>
        </div>

        <div ng-if="complete">

        </div>
    </div>
</div>

JS:

angular.module('test', [])
.controller('TestCtrl', function($scope) {
    $scope.complete = false;

    $scope.items = [
        { name: '2', number: 2 },
        { name: '3', number: 3 },
        { name: '4', number: 4 }
    ];

    $scope.selectedItem = $scope.items[0];

    $scope.getNumber = function (number) {
        return new Array(number);
    };

    $scope.next = function() {
      $scope.complete = true;  
    };
})

Answer 4

ng-if is causing scoping complications that are interfering with the binding process.

For a workaround, you can refer to this updated jsfiddle example. In this solution, another div is wrapped around the elements that need to be hidden. Additionally, a next function is included to ensure that the scope remains consistent when the click event occurs and sets complete to true.

HTML:

<div ng-app="test">
    <div ng-controller="TestCtrl">
        <div ng-if="!complete">
            <div>
                <label for="testAmount">Amount:</label>
                <select id="testAmount" ng-model="selectedItem" ng-options="item.name for item in items"></select>
            </div>

            <form role="form" name="testForm">
                <div ng-repeat="i in getNumber(selectedItem.number) track by $index">
                    {{$index + 'hi'}}
                </div>
                <button class="btn btn-default" value="Next" title="Next" ng-click="next()">Next</button>
            </form>
        </div>

        <div ng-if="complete">

        </div>
    </div>
</div>

JS:

angular.module('test', [])
.controller('TestCtrl', function($scope) {
    $scope.complete = false;

    $scope.items = [
        { name: '2', number: 2 },
        { name: '3', number: 3 },
        { name: '4', number: 4 }
    ];

    $scope.selectedItem = $scope.items[0];

    $scope.getNumber = function (number) {
        return new Array(number);
    };

    $scope.next = function() {
      $scope.complete = true;  
    };
})

Answer 5

Answer №3

It seems like the issue lies in the select statement within an ng-if condition, where the selectedItem is not getting properly set. If you do not want to display the dropdown when !complete, consider using ng-show instead, which should resolve the issue.

    <div ng-show="!complete">

As for why the ng-model is not being bound within the ng-if, it's a bit unclear. It could be due to attempting a conditional bind, which may result in unexpected behavior.

Answer 6

It seems like the issue lies in the select statement within an ng-if condition, where the selectedItem is not getting properly set. If you do not want to display the dropdown when !complete, consider using ng-show instead, which should resolve the issue.

    <div ng-show="!complete">

As for why the ng-model is not being bound within the ng-if, it's a bit unclear. It could be due to attempting a conditional bind, which may result in unexpected behavior.

Using ng-if outside of ng-repeat can cause issues with ng-repeat loops in AngularJS

Answer №1

Answer №2

Answer №3

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