"Download Blob" using Interactive Grid - blob

Question

What is equivalent to the Interactive Report "Download Blob" for Interactive Grids?
Currently I am using an Interactive Report as my workaround but would like to use Interactive Grid however there is no Download Blob column type and I don't want to hack a URL in the select clause.

Answer 1

Here are some steps that show you how it's done in APEX 19.2. Feel free to adjust as needed for other versions of APEX and as per your business requirements.
Create a table to store BLOB files and add a file as an example.
create table files (
id number generated by default as identity,
mime_type varchar2(255),
name varchar2(255),
content blob,
constraint files_pk primary key (id)
)
/
insert into files (
mime_type,
name,
content
) values (
'text/plain',
'test.txt',
hextoraw('48656c6c6f20576f726c6421')
);
commit;
Create a new Interactive Grid page on the table using this query:
select id,
mime_type,
name,
dbms_lob.getlength(content) file_size
from files
Create a new Blank Page in your application. Set Page Number to 9000 and set Name to Download File.
In the left-hand column of the Page Designer, right-click Content Body (under Regions) and select Create Region. Right-click the new region and select Create Page Item. Set the Name of the new item to P9000_FILE_ID and set the Type to Hidden. Note that neither the region or its item will ever be displayed.
In the left-hand column of the Page Designer, open the Pre-Rendering section, right-click Before Header, then select Create Process. Set the Name of the process to Download File and enter the following code for the PL/SQL Code:
declare
l_files_rec files%rowtype;
begin
select *
into l_files_rec
from files
where id = :P9000_FILE_ID;
owa_util.mime_header(l_files_rec.mime_type, false);
htp.p('Content-Length: ' || dbms_lob.getlength(l_files_rec.content));
htp.p('Content-Disposition: attachment; filename="' || l_files_rec.name || '"');
owa_util.http_header_close;
wpg_docload.download_file(l_files_rec.content);
apex_application.stop_apex_engine;
end;
This PL/SQL code is what gets the file from the database and streams it to the browser. You may want to modify this code, for example, to ensure a user should have access to the file they are trying to download. Also, consider application and page level security.
In the Page Designer, return to the Interactive Grid page. Right-click Columns under the Interactive Grid region and select Create Column. Set Column Name to Download, Type to Link, and (under Source) set Type to None. Click the No Link Defined button for Target to open the link settings. Set Page to 9000, use the popup to select P9000_FILE_ID under the Name column, use the popup to select ID under the Value column (in the same row), then click the OK button. Finally, set Link Text (under Target) to download.
To test, run the page and click the download link. The browser should download the file and when you open it the contents should be: Hello World!