Tips for transferring data from one asynchronous function to another in AngularJS

Question

Tips for transferring data from one asynchronous function to another in AngularJS

How to transfer a global variable value between two Angular functions?

Here are the two global variables:

$scope.genewtId = null;
$scope.data1 = null;

The two Angular functions in question are:

$scope.getID = function() {
    Service1.getId("abc").then(function(response){
        $scope.genewtId = response.data[0].Id;
        console.log($scope.genewtId);

    }, function(error){
        console.log(error.statusText);
    });
};

$scope.getDetails = function() {
    Service2.getDetails($scope.genewtId).then(function(response){
        // encountering an error with the response
        $scope.data1 = response.data;
        console.log($scope.data1.toString());
    }, function(error){
        console.log(error.statusText);
    });
};

When attempting to pass the value of $scope.genewtId from one function to another, an error is being received:

message: "Failed to convert value of type 'java.lang.String' to required type 'java.lang.Integer'; nested exception is java.lang.NumberFormatException: For input string: "null"

However, the output of console.log($scope.genewtId); shows a value of 787651, indicating that it is not null.

If there's a way to implement this using $rootScope.$broadcast, please advise.

javascript angularjs angular-promise angularjs-service angularjs-http

Answer 1

Answer №1

The importance of chaining promises in web development

To enhance the functionality of your code, consider modifying the first function to return a promise:

$scope.getID = function() {
    return Service1.getId("abc").then(function(response){
        $scope.genewtId = response.data[0].Id;
        console.log($scope.genewtId);
        return response.data[0].Id;
    }, function(error){
        console.log(error.statusText);
        throw error;
    });
};

Additionally, adapt the second function to both return a promise and accept an argument:

$scope.getDetails = function(id) {
    var genewtID = id || $scope.genewtId;
    return Service2.getDetails(genewtId).then(function(response){
        $scope.data1 = response.data;
        console.log($scope.data1.toString());
        return response.data;
    }, function(error){
        console.log(error.statusText);
        throw error;
    });
};

Subsequently, create a chain of promises by connecting the two functions:

var promise = $scope.getId();

var promise2 = promise.then(function(id) {
                   return $scope.getDetails(id);
               });

var promise2.then(function(data) {
     console.log(data);
}).catch(function(error) {
     console.log(error);
});

Utilizing the .then method facilitates synchronization between promises, ensuring data is retrieved sequentially. You can extend these chains indefinitely, pausing or postponing resolution as needed.

For further insights, refer to:

AngularJS $q Service API Reference - Chaining Promises
You're Missing the Point of Promises

Answer 2

The importance of chaining promises in web development

To enhance the functionality of your code, consider modifying the first function to return a promise:

$scope.getID = function() {
    return Service1.getId("abc").then(function(response){
        $scope.genewtId = response.data[0].Id;
        console.log($scope.genewtId);
        return response.data[0].Id;
    }, function(error){
        console.log(error.statusText);
        throw error;
    });
};

Additionally, adapt the second function to both return a promise and accept an argument:

$scope.getDetails = function(id) {
    var genewtID = id || $scope.genewtId;
    return Service2.getDetails(genewtId).then(function(response){
        $scope.data1 = response.data;
        console.log($scope.data1.toString());
        return response.data;
    }, function(error){
        console.log(error.statusText);
        throw error;
    });
};

Subsequently, create a chain of promises by connecting the two functions:

var promise = $scope.getId();

var promise2 = promise.then(function(id) {
                   return $scope.getDetails(id);
               });

var promise2.then(function(data) {
     console.log(data);
}).catch(function(error) {
     console.log(error);
});

Utilizing the .then method facilitates synchronization between promises, ensuring data is retrieved sequentially. You can extend these chains indefinitely, pausing or postponing resolution as needed.

For further insights, refer to:

AngularJS $q Service API Reference - Chaining Promises
You're Missing the Point of Promises

Answer 3

Answer №2

One potential reason for the issue could be due to the asynchronous nature of promises. The scenario is as follows:

The function

Service2.getDetails($scope.genewtId)

may be getting called before the value of $scope.genewtId is properly set after the promise from Service1.getId("abc").then completes, resulting in the value remaining as null.

To address this problem, consider the following approach:

$scope.getID = function(isCalledAfterDetails) {
    Service1.getId("abc").then(function(response){
        $scope.genewtId = response.data[0].Id;
        console.log($scope.genewtId);
        if(isCalledAfterDetails && $scope.genewtId !== null){
            $scope.getDetails();
        }

    }, function(error){
        console.log(error.statusText);
    });
};

$scope.getDetails = function() {
    if($scope.genewtId === null){
        $scope.getID(true);
    }else{
        Service2.getDetails($scope.genewtId).then(function(response){
            // an error may occur here with the response
            $scope.data1 = response.data;
            console.log($scope.data1.toString());
        }, function(error){
            console.log(error.statusText);
        });
    }

};

While this solution might work, it's advisable to improve the way you structure these function calls. Ensure that $scope.getDetails() does not excessively rely on $scope.getID() for setting the value of $scope.genewtId.

If you require further assistance in implementing a better solution, kindly update your question with specific use cases and additional code snippets.

Updated Solution

$scope.getID = function() {
    Service1.getId("abc").then(function(response){
        $scope.genewtId = response.data[0].Id;
        $scope.getDetails();
    }, function(error){
        console.log(error);
    });
};

$scope.getDetails = function() {
        Service2.getDetails($scope.genewtId).then(function(response){
            // an error may occur here with the response
            $scope.data1 = response.data;
            console.log($scope.data1.toString());
        }, function(error){
            console.log(error.statusText);
        });        
};

Utilizing a Service

In your service.js file

getDetails = function(id){
    var deferred = $q.defer();
    $http.get('/user/'+id).then(function(response){
        var newId = response.data[0].Id;
        $http.get('/user/details'+newId).then(function(details){
            deferred.resolve(details)
        })
    })      
    return deferred.promise;
}

In your controller.js file

$scope.getDetails = function() {
        MySvc.getDetails("abc").then(function(response){
            console.log(response) // your details here
        }, function(error){
            console.log(error.statusText);
        });        
};

Answer 4

One potential reason for the issue could be due to the asynchronous nature of promises. The scenario is as follows:

The function

Service2.getDetails($scope.genewtId)

may be getting called before the value of $scope.genewtId is properly set after the promise from Service1.getId("abc").then completes, resulting in the value remaining as null.

To address this problem, consider the following approach:

$scope.getID = function(isCalledAfterDetails) {
    Service1.getId("abc").then(function(response){
        $scope.genewtId = response.data[0].Id;
        console.log($scope.genewtId);
        if(isCalledAfterDetails && $scope.genewtId !== null){
            $scope.getDetails();
        }

    }, function(error){
        console.log(error.statusText);
    });
};

$scope.getDetails = function() {
    if($scope.genewtId === null){
        $scope.getID(true);
    }else{
        Service2.getDetails($scope.genewtId).then(function(response){
            // an error may occur here with the response
            $scope.data1 = response.data;
            console.log($scope.data1.toString());
        }, function(error){
            console.log(error.statusText);
        });
    }

};

While this solution might work, it's advisable to improve the way you structure these function calls. Ensure that $scope.getDetails() does not excessively rely on $scope.getID() for setting the value of $scope.genewtId.

If you require further assistance in implementing a better solution, kindly update your question with specific use cases and additional code snippets.

Updated Solution

$scope.getID = function() {
    Service1.getId("abc").then(function(response){
        $scope.genewtId = response.data[0].Id;
        $scope.getDetails();
    }, function(error){
        console.log(error);
    });
};

$scope.getDetails = function() {
        Service2.getDetails($scope.genewtId).then(function(response){
            // an error may occur here with the response
            $scope.data1 = response.data;
            console.log($scope.data1.toString());
        }, function(error){
            console.log(error.statusText);
        });        
};

Utilizing a Service

In your service.js file

getDetails = function(id){
    var deferred = $q.defer();
    $http.get('/user/'+id).then(function(response){
        var newId = response.data[0].Id;
        $http.get('/user/details'+newId).then(function(details){
            deferred.resolve(details)
        })
    })      
    return deferred.promise;
}

In your controller.js file

$scope.getDetails = function() {
        MySvc.getDetails("abc").then(function(response){
            console.log(response) // your details here
        }, function(error){
            console.log(error.statusText);
        });        
};

Answer 5

Answer №3

Looks like the issue is originating from the server side.

An error occurred while trying to convert a 'java.lang.String' to an 'java.lang.Integer'; this resulted in a NumberFormatException with the input string being "null".

The message is showing up on the console because of console.log(error.statusText);

You should double-check the logic when using the value in the API.

Answer 6

Looks like the issue is originating from the server side.

An error occurred while trying to convert a 'java.lang.String' to an 'java.lang.Integer'; this resulted in a NumberFormatException with the input string being "null".

The message is showing up on the console because of console.log(error.statusText);

You should double-check the logic when using the value in the API.

Tips for transferring data from one asynchronous function to another in AngularJS

How to transfer a global variable value between two Angular functions?

Answer №1

The importance of chaining promises in web development

Answer №2

Updated Solution

Utilizing a Service

Answer №3

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