Re: AW: [dbforms] BLOB fields and Oracle

[Dziugas Baltrunas]

Hi Henner,
thanks for the answer. Actually I think that this issue isn't a case of 
Oracle, it's more about a "new" blob handling (different to classic one) 
in the jdbforms. As far as I have understood from the code, the main 
difference is (de)serialization, so the new mode does not use FileHolder 
object anymore and therefore must use some blob interceptors in order to 
capture the file name (mainly for the latter use of FileServlet, right?).

However, in the org.dbforms.servlets.FileServlet that mode is 
distinguished depending on fileName:

private void readDbFieldBlob(..) {
<...>
               // classic mode
               if (fileName == null) {
                  ObjectInputStream ois =
                     new ObjectInputStream(blob.getBinaryStream());
                  FileHolder fh = (FileHolder) ois.readObject();
                  writeToClient(
                     request,
                     response,
                     fh.getFileName(),
                     fh.getInputStreamFromBuffer());
               }
               // new mode
               else {
                  writeToClient(request, response, fileName, 
blob.getBinaryStream());
               }
<...>
}

What is more, in the org.dbforms.config.FieldValue class, there is still
a constant reference to the FileHolder object:
case FieldTypes.BLOB :
        res = getFileHolder();
        break;
As I wrote before, my intention is to have a working "new" blob handling 
mode. Currently db:textAreaForBlobs does not work due to the reasons 
stated above. I've already made a patch for db:blobContent tag, but as 
the jdbforms cvs server is down at the moment, I will provide the diff 
later.

Another issue, which is quite a rare one - I want the same blob column 
in the database to be handled with the textarea or file tag regarding to 
some property in the same table. So generaly I need to solve the 
following problems:

1) make the correct handling of new Blob handling mode (get rid of 
FileHolder object).

2) make db:textArea (or/and db:textAreaForBlobs) tag work for Blobs 
(only those handled in new mode or in the classic too?).

3) make the same methods and logic work for blobs irregarding of how 
they were submitted in the form (db:file or db:textArea tag).

4) currently org.dbforms.event.BlobInterceptor code does not care about 
the mime type (size and possibly some other properties) of the uploaded 
file, so this should be somehow fixed too.

I would like to receive some information about the concepts or vision of 
blob handlings in general, so I it would be easier for me to provide the 
correct patches.

Sorry for possible logical mistakes - jdbforms are too big to get the 
flavour in a week or two :)

Dziugas
Henner Kollmann wrote:
Sorry i never worked with blob streams and Oracle!
Feel free to debug and change the source (and send it back to the list)!
Help is welcomed!
Cheers,
Henner

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