Obtain an indeterminate value from a variable

Question

Obtain an indeterminate value from a variable

My situation involves a dynamic variable assigned from a service, requiring a real-time calculator to update another variable using its value.

Below is the relevant code snippet:

$scope.getSubTotalSCTax = function(){
    TableService.checkOut('SubTotal', $scope.DetailMeja.finCheckInID)
    .then(function(response){
        console.log(response);
        $ionicLoading.hide();
        $scope.checkOut = {
            SubTotal: response.SubTotal,
            TaxPercentage: response.TaxPercentage,
            ServiceChargePercentage: response.SCPercentage,
        };
    }, function(err){
        console.log(err);
    })
};
$scope.getSubTotalSCTax();

$scope.checkOut.ServiceCharge = $scope.checkOut.SubTotal * $scope.checkOut.ServiceChargePercentage / 100;
$scope.checkOut.Tax = $scope.checkOut.SubTotal * $scope.checkOut.TaxPercentage / 100;

However, an error stating

TypeError: Cannot read property 'SubTotal' of undefined

occurs at the line

$scope.checkOut.ServiceCharge = $scope.checkOut.SubTotal * $scope.checkOut.ServiceChargePercentage / 100;

*UPDATE : I have included an input type="text" for both Tax Percentage and Service Charge Percentage. These values need to trigger a recalculation each time they are changed.

*UPDATE2 : The recalculation issue has been resolved by utilizing the ng-change event to call a function that runs the recalculate process.

javascript angularjs ionic-framework

Answer 1

Answer №1

It's important to remember that the TableService.checkout function runs asynchronously. This means that the then callback won't be executed until after the rest of your code has finished evaluating.

To handle this, make sure to return the promise from the function.

$scope.calculateSubTotalAndTax = function(){
  var promise = TableService.checkOut('SubTotal',$scope.tableID);

  promise.then(function(response){
    // ...
  });

  return promise;
};

Then, when you call the method, chain another then onto the promise to ensure proper execution order.

$scope.calculateSubTotalAndTax().then(function() {
  $scope.tableServiceCharge = $scope.tableSubTotal * $scope.serviceChargePercentage / 100;
  $scope.tableTax = $scope.tableSubTotal * $scope.taxPercentage / 100;
});

Answer 2

It's important to remember that the TableService.checkout function runs asynchronously. This means that the then callback won't be executed until after the rest of your code has finished evaluating.

To handle this, make sure to return the promise from the function.

$scope.calculateSubTotalAndTax = function(){
  var promise = TableService.checkOut('SubTotal',$scope.tableID);

  promise.then(function(response){
    // ...
  });

  return promise;
};

Then, when you call the method, chain another then onto the promise to ensure proper execution order.

$scope.calculateSubTotalAndTax().then(function() {
  $scope.tableServiceCharge = $scope.tableSubTotal * $scope.serviceChargePercentage / 100;
  $scope.tableTax = $scope.tableSubTotal * $scope.taxPercentage / 100;
});

Answer 3

Answer №2

function calculateTaxAndServiceCharge() {
    return TableService.checkOut('SubTotal', $scope.DetailMeja.finCheckInID)
};

calculateTaxAndServiceCharge().then(function(response) {
    console.log(response);
    $ionicLoading.hide();
    $scope.checkOut.ServiceCharge = response.SubTotal * response.SCPercentage / 100;
    $scope.checkOut.Tax = response.SubTotal * response.TaxPercentage / 100;

}, function(err) {
    console.log(err);
})

Answer 4

function calculateTaxAndServiceCharge() {
    return TableService.checkOut('SubTotal', $scope.DetailMeja.finCheckInID)
};

calculateTaxAndServiceCharge().then(function(response) {
    console.log(response);
    $ionicLoading.hide();
    $scope.checkOut.ServiceCharge = response.SubTotal * response.SCPercentage / 100;
    $scope.checkOut.Tax = response.SubTotal * response.TaxPercentage / 100;

}, function(err) {
    console.log(err);
})

Obtain an indeterminate value from a variable

Answer №1

Answer №2

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