Updating View with AngularJS Scope Variable Fails to Work

Question

Updating View with AngularJS Scope Variable Fails to Work

I've come across this issue quite often on various forums, but none of the solutions I've attempted seem to be working for me. I tried using $apply(), which resulted in an error stating that the digest cycle is already running. The Dot "." notation also didn't yield any changes. I even experimented with timeouts and promises, but unfortunately, the view still doesn't update as expected.

Below is a snippet of the HTML code:

<th colspan="4" ng-class="{'ssqtrue': deficiencies === false , 'ssqfalse': deficiencies === true}">
<span ng-model="definfo">{{definfo}}</span>
    </th>

And here's a portion of my Controller code:

    $scope.recalculateDashboard = function (goToDashboard) {
    contractorService
      .calculateScores()
      .success(function () {
          getscoringDetails();
          getDefInfo();
          if (goToDashboard) {
              $scope.tabs[0].active = true;
          }
      }).error(function (reason) {
          console && console.log(reason.statusText);
          genericErrorAlertHandler();


      });
};

function getDefInfo() {
    contractorService.getDeficiencyInfo()
      .success(function (data) {
            $scope.$apply(function() {
                $scope.definfo = data;
            });
          if ($scope.definfo == 'No Deficiencies Found') {
              $scope.deficiencies = false;
          } else {
              $scope.deficiencies = true;
          }
      }).error(function (reason) {
          console && console.log(reason.statusText);
          genericErrorAlertHandler();


      });
}

I'm at a loss trying to understand what's causing this issue. Any help or guidance would be highly appreciated!

javascript angularjs

Answer 1

Answer №1

Greetings to

<span ng-model="definfo">{{definfo}}</span>

There is no need for the ng-model directive in this case. It's sufficient to use {{definfo}}, or even better, use ng-bind like so:

<span ng-bind="definfo"></span>

I attempted to utilize $apply() which led to an error

Typically, developers use $scope.$apply when receiving a callback from third-party code such as jQuery that operates outside of the digest cycle. It's best not to use it. Alternatively, you can use $timeout for a safer approach, like wrapping it as follows:

 $timeout(function () {
   $scope.definfo = data;
 });

In case you are not using a Promise chain, you can make use of the success and error callbacks (which you have already done) instead of using then()

Regarding

$http.get('/SSQV4/SSQV5/Contractor/GetDeficiencyInfo');

$http.get does return the original Promise, but it also includes additional information such as 'status: Ok', config, headers, etc. You probably do not want to parse the entire response in your controller. Therefore, I suggest creating a new Promise in your service and only fetching the required results.

Instead of just returning $http.get(URL);, I recommend implementing the following in your Service:

  this.getDeficiencyInfo = function () {          
  var deferred = $q.defer(); 
      $http({method: 'GET', url: URL}).then(function(res){
         deferred.resolve(res.data); 
      }, function (error) {
            console.error(error);
            deferred.resolve({error:error}); //you could also reject
        });    
     return deferred.promise;
  };

Check out the DEMO on fiddle

Answer 2

Greetings to

<span ng-model="definfo">{{definfo}}</span>

There is no need for the ng-model directive in this case. It's sufficient to use {{definfo}}, or even better, use ng-bind like so:

<span ng-bind="definfo"></span>

I attempted to utilize $apply() which led to an error

Typically, developers use $scope.$apply when receiving a callback from third-party code such as jQuery that operates outside of the digest cycle. It's best not to use it. Alternatively, you can use $timeout for a safer approach, like wrapping it as follows:

 $timeout(function () {
   $scope.definfo = data;
 });

In case you are not using a Promise chain, you can make use of the success and error callbacks (which you have already done) instead of using then()

Regarding

$http.get('/SSQV4/SSQV5/Contractor/GetDeficiencyInfo');

$http.get does return the original Promise, but it also includes additional information such as 'status: Ok', config, headers, etc. You probably do not want to parse the entire response in your controller. Therefore, I suggest creating a new Promise in your service and only fetching the required results.

Instead of just returning $http.get(URL);, I recommend implementing the following in your Service:

  this.getDeficiencyInfo = function () {          
  var deferred = $q.defer(); 
      $http({method: 'GET', url: URL}).then(function(res){
         deferred.resolve(res.data); 
      }, function (error) {
            console.error(error);
            deferred.resolve({error:error}); //you could also reject
        });    
     return deferred.promise;
  };

Check out the DEMO on fiddle

Answer 3

Answer №2

After some investigation, I was able to solve the issue at hand although the exact reason behind it still eludes me. Upon initial page load, the variable $scope.definfo is populated by data retrieved from a separate http call. This data is stored in the array var pagedata = [], which contains various pieces of information fetched from a service during the page's initial rendering. The scope variable is then updated using the line:

$scope.definfo = pagedata.DeficiencyInfo

. However, removing this line and directly invoking the function getDefInfo achieves the desired result of setting and updating the scope variable. It would be greatly appreciated if one of you knowledgeable individuals could shed some light on why this behavior occurs, so that others facing similar issues may benefit from the explanation. Many thanks to all for the assistance provided.

Answer 4

After some investigation, I was able to solve the issue at hand although the exact reason behind it still eludes me. Upon initial page load, the variable $scope.definfo is populated by data retrieved from a separate http call. This data is stored in the array var pagedata = [], which contains various pieces of information fetched from a service during the page's initial rendering. The scope variable is then updated using the line:

$scope.definfo = pagedata.DeficiencyInfo

. However, removing this line and directly invoking the function getDefInfo achieves the desired result of setting and updating the scope variable. It would be greatly appreciated if one of you knowledgeable individuals could shed some light on why this behavior occurs, so that others facing similar issues may benefit from the explanation. Many thanks to all for the assistance provided.

Updating View with AngularJS Scope Variable Fails to Work

Answer №1

Answer №2

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