Symphony.

I have page parameters one two three which are being used by datasource filters.

I would like to catch those parameters prior to be used for ds evaluation to optionally change their value.

What delegate can I use and, secondly, how do I correctly address those variables?

So far I've used FrontendParamsResolve and e.g. $context['params']['one'] to get the value, but after setting it to e.g. an empty value like $context['params']['one'] = "", the datasource still used the former $one value that came by the GET request.

EDIT:

still used...

I had an idea, it will ignore that parameter and move along.

Where are you trying to grab these parameters? In a custom event or in the data source? If it's in the data source then I think you'd actually need to parse the XML, grab the values, optionally modify them, and then spit them back out as XML to the page.

Where are you trying to grab these parameters?

I have my own extension which uses FrontendParamsResolve to add various params to support the pool.

Some background info:

Page parameters one two three follows the relative URL, that is with an URL /page/subpage/subsubpage/, $one is page, $two is subpage and so on. They are usual page parameters (of index page).

I had an idea that everytime the last of the defined parameters would be of numeric value, e.g. /page/2/ or /page/subpage/2/, I would use that number for DS pagination and not to use it in that case for DS filtering. 'Cause I want to try pagination in this style and not like ?p=2, that is like {$url-p}.

I can not define a pagination page parameter, because the number can be given at any level. The whole page like structure goes from a single index page and is fluid.

Well, I can define a pagination value in that extension based on that, but I can not empty the numeric page param to a NULL or ""; the DS filtering process still counts with the 2 from the request and because of that it fails to match.

Crazy idea no? :/

This is quite easily done with the URL Router extension. You can just make it so that when a numerical regex matches, the (numerical) value is replaced by &pagination=$value. You can then use the $url-pagination parameter in your data-sources.

Something like: ^/(.*)\/([0-9]+)$/ to /$1&pagination=$2 should do the trick (untested!)