How to display download link with get_blob or get_blob_file_src ?

Question

Hello there,
I am struggling to display a download link in a SQL query report.
Based on the requirement, I have to create a sql query report that the source contains a series of union select query.
Example here
WITH current_engagement AS (
SELECT defendant_id, engagement_id, pn, ethnicity, date_joined_aodt_court, case_manager_name
, participation_conditions, discharge_conditions
FROM engagement
WHERE defendant_id = :PXX_DEF
AND date_joined IS NOT NULL
AND ( date_terminated IS NULL OR to_date(date_joined,'DD/MM/YYYY') > to_date(sysdate,'DD/MM/YYYY'))
AND active = 1 AND ROWNUM = 1
ORDER BY defendant_id DESC
SELECT def.first_name, def.middle_name, def.surname, to_char(def.pn) AS "PN", to_char(def.nhi_number) AS "NHI"
,ce.ethnicity, to_char(ce.date_joined) as "DATE_JOINED ", ce.case_manager_name, ce.participation_conditions, ce.discharge_conditions
FROM defendant def INNER JOIN current_engagement ce
ON def.def_id = ce.defendant_id
UNION ALL
select ' <b>2. Phase Number</b>' , '<b>Date Started</b>' , '<b>Date Finised</b>' , '<b>Notes</b>' , null
,null , null , null , null , null
from dual
UNION ALL
SELECT TO_CHAR(NVL(ph.phase_number,'No Phase Found')), TO_CHAR(ph.date_started, 'DD/MM/YYYY'), TO_CHAR(ph.date_finished, 'DD/MM/YYYY'), ph.notes, null
, null , null , null , null , null
FROM phase_membership ph INNER JOIN current_engagement ce
ON ph.mpm_eng_id = ce.engagement_id
WHERE to_date(ph.date_started,'DD/MM/YYYY') <= TO_DATE(sysdate,'DD/MM/YYYY')
AND ( ph.date_finished IS NULL
OR TO_DATE(ph.date_finished, 'DD/MM/YYYY') >= TO_DATE(sysdate,'DD/MM/YYYY') )
AND ph.active = 1
UNION ALL
--more selects
-- then the last select is to list all related documents with download links
select '<b>6. Document Date</b>' , '<b>Document Type</b>' , '<b>Description</b>' , '<b>Download</b>'
, null ,null , null , null , null , null
from dual
UNION ALL
SELECT TO_CHAR(doc.date_received), doc.document_type, doc.comments, TO_CHAR(dbms_lob.getlength(doc.UPLOADED_FILE))
, null ,null , null , null , null , null
FROM document doc INNER JOIN current_engagement ce
ON doc.d_eng_id = ce.engagement_id
WHERE doc.active = 1
This report is generated fine.
But the requirement also ask to display a download link. And because it is union selects, all following selects must be the same as the first select column data types.
In this case, it has to be CHAR. Otherwise, it will generate error as below
ORA-01790: expression must have same datatype as corresponding expression
So I follow the GET_BLOB_FILE_SRC Function step from
http://docs.oracle.com/cd/E14373_01/apirefs.32/e13369/apex_util.htm#AEAPI129
I turn my last select into
SELECT TO_CHAR(doc.date_received), doc.document_type, doc.comments,
CASE WHEN NVL(dbms_lob.getlength(doc.UPLOADED_FILE),0) = 0
THEN NULL
ELSE
'Download'
END
, null ,null , null , null , null , null
FROM document doc INNER JOIN current_engagement ce
ON doc.d_eng_id = ce.engagement_id
WHERE doc.active = 1
Which the result inside the hreg is
http://app_address_here/f?p=208:48:1303335952329758:::::
while if I use Interactive report the link is
http://app_address_here/apex_util.get_blob?s=1303335952329758&a=208&c=66645817090447568&p=48&k1=12&k2=&ck=A18D20D407435BD649EA3399EC27BC00&rt=CR
and it works well.
I do a research and know that get_blob_file_source link to the source of the column / field name located in the first parameter.
So I had put the UPLOADED_FILE column, DOCUMENT table in the source of the column PN.
But it still does not show anything that close to the correct one that is generated by interactive report.
If anyone has any ideas, please help. If I need to manually write using get_blob , please give me an example.
I urgently need to do this report.
The version of APEX we use is Application Express 4.0.2.00.07
And I cannot ask for an upgrade to 4.2 till the end of next year.
Please help.
Thanks a lot in advance.
Ann.

Answer 1

Hi Ann,
Here you can see and download the example :
http://apex.oracle.com/pls/apex/f?p=63066:1
Please let me know if you need access the work space.
Hint, Please read the FAQ section. had you put your thread in a better format, you would have gotten a quicker response :)
Regards,
Fateh