Rails: How to filter results? -

in index action of users controller, able capture users belonging same city current_user in activerecord::relation object @users. in view able iterate through @users , display results. i'd give current_user further options filter results. want add form , filter button in view, allow current_user select filters, such as:

1. minimum age , maximum age (drop down)
2. religion (drop down of checkboxes)
3. diet (drop down of checkboxes)
4. and on.

once current_user makes selections , clicks on filter, results filtered based on criteria selected. want know how build query this?

it's relatively simple without library creating scope methods in user model. example:

 class user     def self.filtered_by_age(opts = {})      min = opts[:min]      max = opts[:max]      user = user.arel_table       if min && max        self.where(:age => min..max)      elsif min && !max        self.where(user[:age].gt(min))      elsif max && !min        self.where(user[:age].lt(max))      else        self.all      end    end   end 

which call with

@users.filtered_by_age(min: 25, max: 52)