Searching multiple related models


I'm interested in some feedback about a solution for searching
multiple related models by columns (as opposed to full-text). A brief
example would be three models with typical has_many relations:
Hotel (name, company)
Room (number, type)
Bed (type, age)

I have a search form that lists the fields for each model with a text
input. Upon submission the search needs to find the results determined
by the refinement criteria entered for each model, so Hotel refines
Room which refines Bed. The results would be a table with each column
dynamically generated based on the criteria entered.

My solution so far has been to produce a set of functions that
recursively goes through the params nested hash starting from the base
model (Hotel) and using the ActiveRecord association reflections to
find out the column type so it can then string together appropriate
conditions, essentially using 'LIKE' for text and '=' for everything
else at the moment.

But working with heavily nested hashes and recursive functions is
hard, and while it mostly works certain aspects are very difficult,
like finding out the column names from the models and putting the
columns in order. I use the human_attribute plugin to set nice column
names in the model, I believe Rails had this but it was removed? :frowning:

So my questions are: is there a common way of doing this? Am I doing
it the right way? Has someone extraced this kind of functionality into
a plugin?

I hope this makes sense without the actual code, I can probably tidy
it and put it up if need be.

Best regards,
Andrew France