Run download method with AWS S3 in Xamarin Forms

FabricioBertani

Hi everyone, i'm testing the Amazon Web Services with S3 cloud and trying to make a simple download test from cloud, but i'm stuck with the code and i need a little push up into the right direction, i try to following this two guides from the AWS docs:
docs.aws.amazon.com/mobile/sdkforxamarin/developerguide/getting-started-store-retrieve-s3-transferutility.html

docs.aws.amazon.com/mobile/sdkforxamarin/developerguide/s3-integration-lowlevelapi.html

When i tryit on i only get asyncs methods and i have absolutely no idea how to implement it, here is some of my code:

public class downloadFile : ContentPage
{
    string filePath = "";
    string bucketName = "***";
    string key = "test.jpg";

    public downloadFile()
    {
        CognitoAWSCredentials credentials = new CognitoAWSCredentials(
            "us-east-1:*****",
            RegionEndpoint.USEast1
        );

        var config = new TransferUtilityConfig();

        var s3Client = new AmazonS3Client(credentials, RegionEndpoint.USEast1);
        var transferUtility = new TransferUtility(s3Client, config);

        TransferUtilityDownloadRequest request = new TransferUtilityDownloadRequest();
        request.BucketName = bucketName;
        request.Key = key;

        transferUtility.DownloadAsync ??????? // Please help me here
    }
}

OurdigiNoahlue

try
{
TransferUtilityDownloadRequest request = new TransferUtilityDownloadRequest();
request.BucketName = "yourS3path";
request.Key = "download.jpg";

            TransferUtility transferUtility = new TransferUtility(client);
            request.WriteObjectProgressEvent += WriteFileProgress;

            System.Threading.CancellationToken cancellationToken = new System.Threading.CancellationToken();
            await transferUtility.DownloadAsync(request, cancellationToken);
        }
        catch (Exception ex)
        {
            System.Diagnostics.Debug.WriteLine("=====ERROR ========");
        }

private void WriteFileProgress(object sender, WriteObjectProgressArgs args)
{
// show progress
System.Diagnostics.Debug.WriteLine("=======UpdateFileProgress=======");
}

OurdigiNoahlue

try
{
TransferUtilityDownloadRequest request = new TransferUtilityDownloadRequest();
request.BucketName = "yourS3path";
request.Key = "download.jpg";

            TransferUtility transferUtility = new TransferUtility(client);
            request.WriteObjectProgressEvent += WriteFileProgress;

            System.Threading.CancellationToken cancellationToken = new System.Threading.CancellationToken();
            await transferUtility.DownloadAsync(request, cancellationToken);
        }
        catch (Exception ex)
        {
            System.Diagnostics.Debug.WriteLine("=====ERROR ========");
        }

private void WriteFileProgress(object sender, WriteObjectProgressArgs args)
{
// show progress
System.Diagnostics.Debug.WriteLine("=======UpdateFileProgress=======");
}

ManoNagarajan

How to find downloaded file in iOS. Do you have any sample.?

kztneda

Hi, I'm actually in the same problem but when I try to download a file I get "System.ArgumentOutOfRangeException" so the app literally breaks out even when I use try-catch. Does any-one know what is happen?

Here is my code:

 using (_clienteS3 = new AmazonS3Client("USER", "PASS", RegionEndpoint.USWest2))
            {
                try
                {    
                    var fileCopyName = Path.Combine(Android.OS.Environment.ExternalStorageDirectory.AbsolutePath, Android.OS.Environment.DirectoryDownloads);

                    TransferUtilityDownloadRequest request = new TransferUtilityDownloadRequest()
                    {
                        BucketName = "BUKET",
                        Key = "FILE.png",
                        FilePath = fileCopyName
                    };

                    TransferUtility transferUtility = new TransferUtility(_clienteS3);

                    await transferUtility.DownloadAsync(request).ConfigureAwait(false); // here the app breaks-out and throws the exception before it closes (the app)
                }
                catch (Exception e) { } //doesn't catch de exception
            }
        }

FabricioBertani

@kztneda did you try to wrap the using(...) with the try/catch instead of using it inside ?
Also looks like you don't set your cognito credentials.

kztneda

are the cognito credentials needed even when the s3 client is logged in?
yep, I tried it.

I don't know what else can I do to get an object