Find conditions from params[]

I have often wished to add a trivial search capability to my controllers which would allow searching on different fields. Without getting into a mess of many different if statements each of which has a different set of conditions, I use something much like the following:

def index
  cond_hash = {}
  cond_strings = []

  if params[:search]
    cond_hash[:login] = "%#{params[:search]}%"
    cond_hash[:email] = "%#{params[:search]}%"
    cond_strings << "(login ILIKE :login OR email ILIKE :email)"
  end
  if params[:search_address]
    cond_hash[:address] = params[:search_address]
    cond_strings << "(address == :address)"
  end

  conditions = cond_strings.join(" AND ")
  @users = User.all :conditions => [ conditions, cond_hash ]
end

It may be safer to use users.login, users.email, and users.address in the SQL-like strings above.