Forum OpenACS Q&A: Squirting out CSV files

Good afternoon The List,

I'm presently trying to output CSV using Listbuilder, and I've got the data displaying OK on screen, however what I am aiming for is for the user to click on the link and be presented with an Open/Save As dialogue, ostensibly for Excel.

I've worked out that I can use doc_return to return the result as a document of the correct content type, however the data's generated by an <include> which contains the Listbuilder stuff, and doc_report requires a data string to return.

The only way I can think of is to use ns_httpopen to hit the CSV generation page (using 127.0.0.1 as the web host), take the output and then send that out using doc_return, however that seems like an unecessarily complicated route to take.

Even if the Listbuilder call wasn't inside an include I'd still need a workaround, as the list data wouldn't be rendered as CSV output until the <listtemplate> tag in its ADP page was hit, and using doc_return with the template::list variable would mean the server would never reach that point. Or have I made a wrong assumption somewhere along the line ?

The documentation I'm looking at says doc_return is a wrapper for ns_return, however the panoptic.com entry for ns_return isn't exactly informative...

Any pointers much appreciated !!

Jason

Hiya all,

I've been playing with this on and off, and template::list::write_csv does 
*almost* what I want, however it seems that inside it returns its results
with 

   ns_return 200 text/plain $__output

what I need is either that output sent back into a string variable so I can
do something with it, or to have a function identical to
template::list::write_csv that returns with something like

   set headers [ns_set new myheaders]
   ns_set put $headers "Content-disposition" \
      "attachment; filename=$output_file_name"
   ns_respond -status 200 \
      -type $mime_type \
      -string $__output \
      -headers $headers

in place of the ns_return statement that currently exists there.

Does anyone know of a function that already does what I want, or will this
have to be a change to the copy of list-procs.tcl that we're using ?

Cheers,

Jason

The solution you have come up with is the same one I did a while back. One recommendation that I have for you, in order to ease upgradeability, is to create a package for your site named something like packages/mysite and put your new proc a /packages/mysite/tcl/mysite-customized-procs-init.tcl file, which would reference where the original procs are from and what you customized via a comment that is something like:

# From acs-templating/tcl/list-procs.tcl
# changed return make csv download as an
# attachment

ad_proc -public template::list::write_output {
...

This file would contain all procs you customize for your site. That way when you do an upgrade to a new version of acs-templating your customized proc would remain active. Packages are sourced alphabetically first with the -procs files then the -init files. Your custom proc will be initialized after all the procs files load since its an init file thus upgrading won't override your customized procs.

I used to document changes that I needed to make to a bunch of packages and every upgrade was a hassel since I had to redo all my changes - which got trickier and tricker the more i customized. Now, when I upgrade, I simply look in my /packages/mysite/tcl/mysite-customized-procs-init.tcl file and compare those procs to the ones that are in the upgraded packages. If there are differences, especially security changes, between the new ones and the procs I customized off of I choose what and how to modify my custom proc to match the changes made by the upgrade and my sites custom needs. Most of the procs I customized aren't changed with every upgrade so I don't have to do any customizations to those procs to keep running the way my users expect it to.

I hope this helps.