Gem/plugin for AJAX advance search (multiple params)


Does someone know a Gem or a plugin that can help me building something like this advance search:

I like it because it knows if it is an integer field or string field and automatically fill the select field with the correct options (greater than, equal than, etc).

Or should I just try to implement my own solution, copying and pasting somethings from admin_data?

Redmine has something similar:

In one hand, it fills the select field better then admin_data when there is a table relationship but on the other hand I can’t add 2 filters for the same field. For example, I can’t search issues with “% done” greater then 20 AND less then 70.