AngularJS application: unable to update $index

Question

I am working on an app in AngularJS 1.6, using the Giphy.com api.

There is a Plunker HERE .

I iterate over an array of "giphys"coming from https://api.giphy.com/v1/gifs/trending?api_key=myApyKey and display them into Bootstrap 4 cards.

There is a view single giphy functionality . In the controller I have:

// Create controller for the "giphyApp" module
app.controller("giphyCtrl", ["$scope", "$http", "$filter", "$timeout", function($scope, $http, $filter, $timeout) {
  var url = "https://api.giphy.com/v1/gifs/trending?api_key=PTZrBlrq8h2KUsRMeBuExZ5nHyn7dzS0&limit=120&rating=G";
  $scope.giphyList = [];
  $scope.search = "";
  $scope.filterList = function() {
    var oldList = $scope.giphyList || [];
    $scope.giphyList = $filter('filter')($scope.giphys, $scope.search);
    if (oldList.length != 0) {
      $scope.pageNum = 1;
      $scope.startAt = 0;
    };
    $scope.itemsCount = $scope.giphyList.length;
    $scope.pageMax = Math.ceil($scope.itemsCount / $scope.perPage);
  };

  $http.get(url)
  .then(function(data) {
      // giphy arary
      $scope.giphys = data.data.data;
      $scope.filterList();
      console.log($scope.giphys);

      // Paginate
      $scope.pageNum = 1;
      $scope.perPage = 24;
      $scope.startAt = 0;
      $scope.filterList();

      $scope.currentPage = function(index) {
        $("html, body").animate({
          scrollTop: 0
        }, 500);
        $timeout( function(){
          $scope.pageNum = index + 1;
          $scope.startAt = index * $scope.perPage;
        },0);
      };

      $scope.prevPage = function() {
        if ($scope.pageNum > 1) {
          $scope.pageNum = $scope.pageNum - 1;
          $scope.startAt = ($scope.pageNum - 1) * $scope.perPage;
        }
      };

      $scope.nextPage = function() {
        if ($scope.pageNum < $scope.pageMax) {
          $scope.pageNum = $scope.pageNum + 1;
          $scope.startAt = ($scope.pageNum - 1) * $scope.perPage;
        }
      };

      $scope.selectedIndex = null;
      $scope.selectedGiphy = null;

      $scope.fetchSinglegGiphy = function(giphy, index) {
        console.log(index);
        $scope.selectedIndex = index;
        $scope.selectedGiphy = giphy;
      }
    });
}]);

The Grid

<div class="row grid" ng-if="giphyList.length > 0">
  <div data-ng-repeat="giphy in giphyList | limitTo : perPage : startAt" 
       class="col-xs-12 col-sm-6 col-lg-4 col-xl-3 d-flex mb-4">
    <div class="giphy d-flex flex-column w-100">
      <div class="thumbnail pb-2 text-center" data-toggle="modal"
           data-target="#giphyModal"
           ng-click="fetchSinglegGiphy(giphy, $index)">
        <img ng-src="{{giphy.images.downsized.url}}" class="img-fluid">
      </div>
      <div class="text mt-auto">
        <p class="m-0 meta">{{giphy.import_datetime | dateParse | date : "MMMM dd y" }}</p>
        <p class="rating m-0">
          <i class="fa fa-star" aria-hidden="true"></i> {{giphy.rating | capitalize}}
        </p>
        <ul class="list-unstyled mb-0 text-center">
          <li ng-if="giphy.username != ''" class="text-muted">{{giphy.type | capitalize}} file uploaded by
            <br><strong>{{giphy.username | capitalize }}</strong>
          </li>
          <li ng-if="giphy.username == ''" class="text-muted">{{giphy.type | capitalize}} file uploaded by
            <br> <strong>Unknown</strong>
          </li>
          <li class="h6">{{giphy.title | titlecase }}</li>
        </ul>
      </div>
    </div>
  </div>
</div>

The Modal

<div class="modal fade" id="giphyModal">
  <div class="modal-dialog">
    <div class="modal-content">
      <div class="modal-header">
        <h4 class="modal-title h-3">{{selectedGiphy.title | titlecase }}</h4>
        <button type="button" class="close" data-dismiss="modal">
        <span>&times;</span>
        </button>
      </div>
      <div class="modal-body">
        <div class="row">
          <div class="col-12">
            <div class="image image text-center">
              <img ng-src="{{selectedGiphy.images.original.url}}"
                   alt="{{selectedGiphy.title }}" class="img-fluid">
            </div>
          </div>
        </div>
      </div>
      <div class="modal-footer justify-content-between">
        <div class="text-muted">Image ID: {{selectedGiphy.id}}</div>
        <div class="btn-group btn-group-sm">
          <button type="button" class="btn btn-success" data-dismiss="modal">
             <i class="fa fa-times-circle"></i> Close
          </button>
        </div>
      </div>
    </div>
  </div>
</div>

This part of the application works fine.

I had expected to be able to easily add a next and previous giphy to the modal above:

<div class="controls text-center">
    <a href="#" ng-click="fetchSinglegGiphy(giphy, $index = $index - 1)" class="left">
      <i class="fa fa-chevron-left"></i>
    </a>
    <a href="#" ng-click="fetchSinglegGiphy(giphy, $index = $index + 1)" class="right">
      <i class="fa fa-chevron-right"></i>
    </a>
</div>

To my surprise this does not work. When I click any one of the controls, the GIF file remains the same, wile all the text in the modal disappears.

Questions:

1. What is wrong with this approach?
2. Do you see a viable alternative?

Answer 1

When I click any one of the controls, the GIF file remains the same

Check to see if giphy equals what you expect:

$scope.fetchSinglegGiphy = function(giphy, index) {
   $scope.selectedIndex = index;
   $scope.selectedGiphy = giphy;
   if ( giphy != $scope.giphyList[index] ) {
      $scope.selectedGiphy = $scope.giphyList[index];
   };
};

Update the selectedGiphy in the case that it is not.

Answer 2

You not only use $index outside of the ng-repeat block, but also you use giphy outside of that block, where it is not defined.

I assume you have $scope.giphyList defined in your controller. So all you have to do is to send the index.

$scope.selectedIndex = null;
$scope.selectedGiphy = null;

$scope.fetchSinglegGiphy = function(index) {
   $scope.selectedIndex = index;
   $scope.selectedGiphy = $scope.giphyList[index];
}

<div class="controls text-center">
    <a href="#" ng-click="fetchSinglegGiphy(selectedIndex-1)" class="left">
      <i class="fa fa-chevron-left"></i>
    </a>
    <a href="#" ng-click="fetchSinglegGiphy(selectedIndex+1)" class="right">
      <i class="fa fa-chevron-right"></i>
    </a>
</div>

I hope this helps, Cheers

Answer 3

index.html

<div class="modal fade" id="giphyModal">
   <div class="modal-dialog">
      <div class="modal-content">
         <div class="controls text-center">
            <a href="#" ng-click="fetchSinglegGiphyModal('prev')" class="left"><i class="fa fa-chevron-left"></i></a>
            <a href="#" ng-click="fetchSinglegGiphyModal('next')" class="right"><i class="fa fa-chevron-right"></i></a>
         </div>
         <div class="modal-header">
            <h4 class="modal-title h-3">
               {{ selectedGiphy.title | capitalize }}
            </h4>
            <button type="button" class="close" data-dismiss="modal">
               <span>&times;</span>
            </button>
         </div>
         <div class="modal-body">
            <div class="row">
               <div class="col-12">
                  <div class="image image text-center">
                     <img ng-src="{{ selectedGiphy.images.original.url }}" alt="{{ selectedGiphy.title }}" class="img-fluid" image-on-load ng-hide="modalImageLoading" />
                     <div class="spinner-border" ng-if="modalImageLoading"></div>
                  </div>
               </div>
            </div>
         </div>
         <div class="modal-footer justify-content-between">
            <div class="text-muted">
               Image ID: {{ selectedGiphy.id }}
            </div>
            <div class="btn-group btn-group-sm">
               <button type="button" class="btn btn-success" data-dismiss="modal">
                  <i class="fa fa-times-circle"></i> Close
               </button>
            </div>
         </div>
      </div>
   </div>
</div>

MODIFICATIONS:

<a href="#" ng-click="fetchSinglegGiphyModal('prev')" class="left"><i class="fa fa-chevron-left"></i></a>
<a href="#" ng-click="fetchSinglegGiphyModal('next')" class="right"><i class="fa fa-chevron-right"></i></a>

fetchSinglegGiphyModal handles both previous and next Giphy based on the condition that acts on the argument prev or next value that we pass in the function.

I have also added the following code to introduce loader which comes with bootstrap to indicate that GIF image is being loaded in the background.

<div class="image image text-center">
   <img ng-src="{{ selectedGiphy.images.original.url }}" alt="{{ selectedGiphy.title }}" class="img-fluid" image-on-load ng-hide="modalImageLoading" />
   <div class="spinner-border" ng-if="modalImageLoading"></div>
</div>

app.js

$scope.modalImageLoading = false;

$scope.fetchSinglegGiphy = function (giphy, index) {
   $scope.selectedIndex = index;
   $scope.selectedGiphy = giphy;
   $scope.modalImageLoading = true;
};

$scope.fetchSinglegGiphyModal = function (dir) {
   let selectedGiphy = null;
   if (dir === "prev") $scope.selectedIndex -= 1; // To load previous
   else if (dir === "next") $scope.selectedIndex += 1; // To load next

   selectedGiphy = $scope.giphyList[$scope.selectedIndex];
   if (selectedGiphy) {
      $scope.selectedGiphy = selectedGiphy;
      $scope.modalImageLoading = true;
   }
};

$scope.fetchSinglegGiphyModal acts on the condition we pass in the parameter and shows the corresponding Giphy data.

I have implemented a custom directive to show the image element and hide the loader when the image is downloaded. Here is the directive code:

app.directive('imageOnLoad', function () {
   return {
      restrict: 'A',
      controller: 'giphyCtrl',
      link: function (scope, element, attrs) {
         element.bind('load', function () {
            scope.$apply(function () {
               scope.modalImageLoading = false;
            });
         });
      }
   }
});

Here is the modified plunker code .

Hope it helps!

Answer 4

Where you move the giphy to the modal, you should also send the $index (as you really did), so in the modal you know who your index is, regardless of $index.

<div class="controls text-center">
    <a href="#" ng-click="fetchSinglegGiphy(giphy, selectedIndex - 1)" class="left"><i class="fa fa-chevron-left"></i></a>
    <a href="#" ng-click="fetchSinglegGiphy(giphy, selectedIndex + 1)" class="right"><i class="fa fa-chevron-right"></i></a>
 </div>