irule class match each query param separately

I think it would almost make more sense to just reorder the params, and then look them up in the data group. So something like this:

when HTTP_REQUEST {
   if { [URI::query [HTTP::uri]] ne "" } {
      set param1 [URI::query "?[URI::query [HTTP::uri]]" param1]
      set param2 [URI::query "?[URI::query [HTTP::uri]]" param2]
      set param3 [URI::query "?[URI::query [HTTP::uri]]" param3]

      set paramstring "param1=$param1&param2=$param2&param3=$param3"

      if { [class match $paramstring equals dg1] } {
         ... do something here ...
      }
   }
}

You'll of course need some additional error checking in there, to make sure params exist, but you get the idea.