How to filter info and keep everything DRY

Hey, I'm trying to give this problem the best solution possible:

I have a posts and an events model
both have categories, tags and belong both to users and groups

Now I need to filter results by any of the above, let it be category,
tag, user or group. What is the best way to do this?

I'm thinking of passing a variable in params[:whatever] and then have
a case in the controller and rendering the apropiate view. But it
doesnt feel right or very REST-y

Can anyone help with this? thanx.

I am facing a similar problem. Does anyone knows how to make this REST-