Scout/HowTo/3.9/Transfer a file from the client to the server

The Scout documentation has been moved to https://eclipsescout.github.io/.

This tutorial describes how to transfer a file from the client to the server by using RemoteFile.

Create the Form

1. Create a new form (name: UploadFileForm, no form id, no modify handler, no permissions).
2. Add a new file chooser field to the main box (name: FileField).
3. In Scout Object Properties view, choose Type Load and Mandatory in Behavior for the newly created field.
4. Add a new variable named RemoteFile (Bean type RemoteFile) to the form.

Add File Upload Code

Overwrite execStore of the NewHandler as follows:

File file = getFileField().getValueAsFile();
String name = IOUtility.getFileName(file.getAbsolutePath());
String fileExtension = IOUtility.getFileExtension(name);
try {
  RemoteFile remoteFile = new RemoteFile(name, System.currentTimeMillis());
  remoteFile.readData(new FileInputStream(file));
  remoteFile.setContentLength((int) file.length());
  remoteFile.setContentTypeByExtension(fileExtension);
  setRemoteFile(remoteFile);
}
catch (IOException e) {
  throw new ProcessingException("Could not remote file", e);
}
 
IUploadFileService service = SERVICES.getService(IUploadFileService.class);
UploadFileFormData formData = new UploadFileFormData();
exportFormData(formData);
formData = service.create(formData);

Add Menu to Open Form

1. Add a new sub menu to the Desktop / FileMenu (name UploadFileMenu).
2. Overwrite execAction of the new menu as follows:

UploadFileForm form = new UploadFileForm();
form.startNew();
form.waitFor();

Server Side Handling

Use the following code in the create method of the UploadFileService:

try {
  // get content from remote file
  ByteArrayOutputStream bos = new ByteArrayOutputStream();
  formData.getRemoteFile().writeData(bos);
  bos.flush();
  byte[] content = bos.toByteArray();
 
  int updated = SQL.update("" +
      " UPDATE FILES " +
      "    SET CONTENT = :content " +
      "  WHERE FILENAME = :filename "
      , new NVPair("filename", formData.getRemoteFile().getName())
      , new NVPair("content", content)
      );
 
  if (updated == 0) {
    SQL.insert("" +
        " INSERT INTO FILES " +
        "    (FILENAME, CONTENT) " +
        "   VALUES " +
        "    (:filename, :content) "
        , new NVPair("filename", formData.getRemoteFile().getName())
        , new NVPair("content", content)
        );
  }
}
catch (IOException e) {
  throw new ProcessingException("Could not persist remote file.", e);
}
return formData;

Now you are able to open the new form via the menu, choose a file to upload, and handle the file content on server side.