Easily finding attributes from Ext.grid.GroupingView's xml calls

I have a ext.GroupingView grid that paginates, filters, and obviously

The combination of these options is both awesome and beyond the scope
of this discussion.

The problem is, the params request when a user wants a new set of
results is something that bears no resemblance to the database schema.

I’ve ended up doing something like this:

That looks like hell, I’m not sure it works, and I dread the idea of
maintaining it.

Is there a better solution out there? For those not wanting to look at
the horrors beyond that link, I need something to take a filter string
with a value, an offset, a group key, a limit, a sort key with
ASC|DESC, and turn it into a query that spits out an array of objects
sorted first by group and then again by sort.

Thanks in advance -