BLOB download via WPG_DOCLOAD not working: what's with the document table?

Question

Hi,
We upgrade our APEX application to 4.2 on RDBMS 11.2.0.1.0, and now our file downloads are failing with 404-not found errors.
Documents are stored as BLOBs in a dedicated table TICKETDOC. Uploading works fine via APEX, I can query the docs in the table and all is looking fine so far.
I have a report column formatted as HTML, making it a clickable thumbnail which should open the file in a separate browser window when clicked.
HTML format for column:
+*
<img src="#OWNER#.DOWNLOAD_FILE?p_id=#THUMBNAIL#" height=40">
</a>
*+
This is supposed to call our own procedure TICKET.DOWNLOAD_FILE, which calls WPG_DOCLOAD:
+*
create or replace
PROCEDURE "DOWNLOAD_FILE" (p_id in number) AS
l_mime varchar2(255);
l_length number;
l_file_name varchar2(2000);
lob_loc BLOB;
v_found BOOLEAN := FALSE;
CURSOR c_doc IS
SELECT doctype, doc, naam, DBMS_LOB.GETLENGTH(doc)
FROM ticketdoc
WHERE ticketdocid = p_id;
CURSOR c_mail IS
SELECT mimetype, content_attachment, filenaam, DBMS_LOB.GETLENGTH(content_attachment)
FROM mailattachment
WHERE mailattachmentid = p_id;
param_val owa.vc_arr;
p_table Varchar2(200);
l_errm varchar2(2000);
BEGIN
p_table := 'TICKETDOC';
IF p_table = 'TICKETDOC' THEN
OPEN c_doc;
FETCH c_doc INTO l_mime, lob_loc, l_file_name, l_length;
IF c_doc%FOUND THEN
v_found := TRUE;
else
END IF;
CLOSE c_doc;
ELSIF p_table = 'MAILATTACHEMENT' THEN
OPEN c_mail;
FETCH c_mail INTO l_mime, lob_loc, l_file_name, l_length;
IF c_mail%FOUND THEN
v_found := TRUE;
END IF;
CLOSE c_mail;
END IF;
IF v_found THEN
--initialise owa with some environment variable
param_val (1) := 1;
owa.init_cgi_env(param_val) ;
-- Set up HTTP header
-- Use an NVL around the mime type and if it is a null, set it to
-- application/octect - which may launch a download window from windows
owa_util.mime_header(nvl(l_mime,'application/octet-stream'), FALSE );
-- Set the size so the browser knows how much to download
htp.p('Content-length: ' || l_length);
-- The filename will be used by the browser if the users does a "Save as"
htp.p('Content-Disposition: attachment; filename="' || l_file_name || '"');
-- Close the headers
owa_util.http_header_close;
-- Download the BLOB
wpg_docload.download_file( Lob_loc );
END IF;
exception
when others then
l_errm := sqlerrm;
raise;
END;
*+
The idea is to display a thumbnail image which, when clicked, will open the document (image, pdf, whatever) in a new browser window.
Executing the procedure in SQLDeveloper works fine and I can query the downloaded BLOB (getlength etc).
However, when I click the thumbnail in the APEX application I get a 404.
Enabling debug via exec dbms_epg.set_dad_attribute('APEX', 'error-style', 'DebugStyle') yields the following:
+*
Fri, 31 May 2013 09:41:35 GMT
Error retrieving document.
Please verify that the document you requested exists in the document table
DAD name: apex
PROCEDURE : TICKET.DOWNLOAD_FILE
URL : http://XDB HTTP Server:8080/apex/TICKET.DOWNLOAD_FILE?p_id=1091
PARAMETERS :
===========
p_id:
1091
ENVIRONMENT:
============
PLSQL_GATEWAY=WebDb
GATEWAY_IVERSION=2
SERVER_SOFTWARE=Oracle Embedded PL/SQL Gateway/11.2.0.1.0
GATEWAY_INTERFACE=CGI/1.1
SERVER_PORT=8080
SERVER_NAME=XDB HTTP Server
REQUEST_METHOD=GET
QUERY_STRING=p_id=1091
PATH_INFO=/TICKET.DOWNLOAD_FILE
SCRIPT_NAME=/apex
REMOTE_HOST=
REMOTE_ADDR=127.0.0.1
SERVER_PROTOCOL=HTTP/1.1
REQUEST_PROTOCOL=HTTP
REMOTE_USER=ANONYMOUS
ORACLE_SSO_USER=
OSSO_IDLE_TIMEOUT_EXCEEDED=
OSSO_USER_GUID=
HTTP_CONTENT_LENGTH=0
HTTP_CONTENT_TYPE=
HTTP_USER_AGENT=Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; WOW64; Trident/5.0)
HTTP_HOST=localhost:8080
HTTP_ACCEPT=text/html,application/xhtml+xml,*/*
HTTP_ACCEPT_ENCODING=gzip,deflate
HTTP_ACCEPT_LANGUAGE=nl-BE,en-US;q=0.5
HTTP_ACCEPT_CHARSET=
HTTP_COOKIE=__utmc=31852350; __utmz=31852350.1366364489.1.1.utmccn=(direct)|utmcsr=(direct)|utmcmd=(none); __utma=31852350.974780296.1366364489.1366364489.1369990367.2; ORA_WWV_USER_61804796552973=930EBD5017F98F039F659148EAE74140; ORA_WWV_REMEMBER_UN=JO:ticket; ORA_WWV_F4000_P4150_TREE=RenderingTree%3A3727930518286945_columns%3A3729417793306453; SHARED_SESSION=87D7D96BC5A457924CB86A817315D30E; [email protected]
HTTP_IF_MODIFIED_SINCE=
HTTP_REFERER=http://10.0.25.1/apex/f?p=101:40:7036965658754:::::
HTTP_SOAPACTION=
HTTP_ORACLE_ECID=
HTTP_ORACLE_CACHE_VERSION=
HTTP_AUTHORIZATION=
WEB_AUTHENT_PREFIX=
DAD_NAME=apex
DOC_ACCESS_PATH=docs
DOCUMENT_TABLE=wwv_flow_file_objects$
PATH_ALIAS=
REQUEST_CHARSET=AL32UTF8
REQUEST_IANA_CHARSET=UTF-8
SCRIPT_PREFIX=
HTTP_IF_MATCH=
HTTP_CACHE_CONTROL=
SOAP_BODY=
HTTP_X_ORACLE_DEVICE_CLASS=
HTTP_X_ORACLE_DEVICE_ORIENTATION=
HTTP_X_ORACLE_DEVICE_MAXDOCSIZE=
HTTP_X_ORACLE_DEVICE=
HTTP_X_ORACLE_ORIG_ACCEPT=
HTTP_X_ORACLE_ORIG_USER_AGENT=
HTTP_X_ORACLE_USER_LOCALE=
HTTP_X_ORACLE_USER_NAME=
HTTP_X_ORACLE_USER_DISPLAYNAME=
HTTP_X_ORACLE_USER_USERKIND=
HTTP_X_ORACLE_USER_AUTHKIND=
HTTP_X_ORACLE_USER_DEVICEID=
HTTP_X_ORACLE_USER_LOCATION_ADDRESSLINE1=
HTTP_X_ORACLE_USER_LOCATION_ADDRESSLINE2=
HTTP_X_ORACLE_USER_LOCATION_ADDRESSLASTLINE=
HTTP_X_ORACLE_USER_LOCATION_BLOCK=
HTTP_X_ORACLE_USER_LOCATION_CITY=
HTTP_X_ORACLE_USER_LOCATION_COMPANYNAME=
HTTP_X_ORACLE_USER_LOCATION_COUNTY=
HTTP_X_ORACLE_USER_LOCATION_STATE=
HTTP_X_ORACLE_USER_LOCATION_POSTALCODE=
HTTP_X_ORACLE_USER_LOCATION_POSTALCODEEXT=
HTTP_X_ORACLE_USER_LOCATION_COUNTRY=
HTTP_X_ORACLE_USER_LOCATION_TYPE=
HTTP_X_ORACLE_USER_LOCATION_X=
HTTP_X_ORACLE_USER_LOCATION_Y=
HTTP_X_ORACLE_SERVICE_HOME_URL=
HTTP_X_ORACLE_SERVICE_PARENT_URL=
HTTP_X_ORACLE_HOME_URL=
HTTP_X_ORACLE_MODULE_CALLBACK_URL=
HTTP_X_ORACLE_MODULE_CALLBACK_LABEL=
HTTP_X_ORACLE_CACHE_USER=
HTTP_X_ORACLE_CACHE_SUBID=
HTTP_X_ORACLE_CACHE_AUTH=
HTTP_X_ORACLE_CACHE_DEVICE=
HTTP_X_ORACLE_CACHE_LANG=
HTTP_X_ORACLE_CACHE_ENCRYPT=
HTTP_X_ORACLE_ASSERT_USER=
*+
I made minor adjustments to the original (pre-4.2) code:
* initialised owa with some environment variable
* registered DOWNLOAD_FILE in wwv_flow_epg_include_mod_local
but still no success.
Any ideas on how to fix this?
Greetz
Jo

Answer 1

As I understand:
The procedure works.
The link 'appears' to work. (ie you saw the procedure run a 2nd at the database level)
But it doesn't actually work (because you get a 404)
I think I ran into an issue, on a completely different page type, that produced an 'error 404'. (I can't seem to reproduce it, though)
The only way I discovered what was really going on was with an HTTP sniffer. (eg HTTPFox for FireFox)
Through that, I noticed that the browser was (for some reason) calling a completely non-sensible APEX page. (hence the PAGE NOT FOUND error)
My solution was to add a "submit to self" branch point.
If that doesn't work, I'm at a loss.
MK