File removal overtakes file download from fileStorage, therefore FileStorageException: File not found given

Support
#1

Hi All,

There is a feature in our app where users can upload a .csv file. Then it will be processed, modified and downloaded to the user’s pc. Then the app removes it from the fileStorage. Now I’ve found it a little bit tricky, because the file removal overtakes the file download. Solved it with a new Thread and sleep it until the file download finishes but come on… :sweat_smile:

Here is the original method (without thread sleep), invoked by a button:

    public void uploadAndImportCsv() {
        FileUploadDialog dialog = (FileUploadDialog) screens.create("fileUploadDialog", OpenMode.DIALOG);
        dialog.addAfterCloseListener(event -> {
            UUID fileId = dialog.getFileId();
            String fileName = dialog.getFileName();
            try {
                dataImportService.asd(fileUploadingAPI.getFile(fileId));
                FileDescriptor fileDescriptor = fileUploadingAPI.getFileDescriptor(fileId, fileName);
                fileDescriptor.setName(OPPORTUNITY_ERRORS_CSV);
                fileUploadingAPI.putFileIntoStorage(fileId, fileDescriptor);
                dataManager.commit(fileDescriptor);
                exportDisplay.show(fileDescriptor);
                fileStorageService.removeFile(fileDescriptor);
            } catch (FileStorageException e) {
                log.error(e.getMessage());
            }
        });
        screens.show(dialog);
    }

Any idea how can I make it work without thread sleep and any black magic?

Thanks,
Balázs

#3

Hello,

Take a look at background tasks (see documentation). Background tasks mechanism performs tasks asynchronously without blocking the user interface. It also can show the progress dialog of the task.

For instance,

Background task class 
private class DownloadFileTask extends BackgroundTask<Void, FileDescriptor> {

    private FileDescriptor fd;

    public DownloadFileTask(FileDescriptor fd) {
        super(5, TimeUnit.SECONDS, TestScreen.this);
        this.fd = fd;
    }

    @Override
    public FileDescriptor run(TaskLifeCycle<Void> taskLifeCycle) throws Exception {
        return fd;
    }

    @Override
    public void done(FileDescriptor result) {
        exportDisplay.show(result);
    }
}
Task progress listener 
private class DownloadFileTaskProgressListener extends BackgroundTask.ProgressListenerAdapter<Void, FileDescriptor> {
    @Override
    public void onDone(FileDescriptor result) {
        try {
            fileStorageService.removeFile(result);
            dataManager.remove(result);
        } catch (FileStorageException e) {
            log.error("Cannot remove file", e);
        }
    }
}
FileUploadDialog code 
public void uploadAndImportCsv() {
    FileUploadDialog dialog = (FileUploadDialog) screens.create("fileUploadDialog", OpenMode.DIALOG);
    dialog.addAfterCloseListener((event) -> {
        if (event.closedWith(StandardOutcome.COMMIT)) {
            UUID fileId = dialog.getFileId();
            String fileName = dialog.getFileName();
            try {
                dataImportService.asd(fileUploadingAPI.getFile(fileId));

                FileDescriptor fileDescriptor = fileUploadingAPI.getFileDescriptor(fileId, fileName);
                fileDescriptor.setName(OPPORTUNITY_ERRORS_CSV);
                fileUploadingAPI.putFileIntoStorage(fileId, fileDescriptor);
                dataManager.commit(fileDescriptor);

                DownloadFileTask task = new DownloadFileTask(fileDescriptor);
                task.addProgressListener(new DownloadFileTaskProgressListener());
                BackgroundWorkWindow.show(task);
            } catch (FileStorageException e) {
                log.error("Cannot save file", e);
            }
        } else if (event.closedWith(StandardOutcome.CLOSE)) {
            // do something
        }
    });
    screens.show(dialog);
}