Rails - basic filtering & sorting

events_controller.rb

class EventsController < ApplicationController

  def index

    # start with default filtering (usually no filtering)
    @events = Event.all

    # custom (user-chosen) filtering
    if params[:filters].present?
      # you can check for all the different filter values you want to allow. first is future/current/past
      if params[:filters][:when] == 'now'
        @events = @events.where(['start_time < ?', DateTime.now]).where(['end_time > ?', DateTime.now])
      elsif params[:filters][:when] == 'future'
        @events = @events.where(['start_time > ?', DateTime.now])
      elsif params[:filters][:when] == 'past'
        @events = @events.where(['end_time < ?', DateTime.now])
      end
      
      # zip
      if params[:filters][:zip].to_i.present?
        # hardcode distance to 25 miles for now
        # need to add a custom method or custom scope to Event class named 'near',
        # or change this code to use a function you got from a gem
        @events = @events.near(params[:filters][:zip].to_i, 25)
      end
    end

    # sorting
    if params[:sort].present?
      # sort in reverse order if the sort param starts with a hyphen
      # allows you to create links like ....&sort=name...   or  ....&sort=-name.... for reverse order by name
      if params[:sort].start_with?('-')
        sortby = params[:sort].sub(/^-/, '') + ' DESC'
      end
      # then add the sort param to the events query
      @events = @events.order(sortby)
    else
      # default sort
      @events = @events.order('created_at DESC')
    end
    
    # check out the will_paginate gem if you want to enable pagination (page=1, page=2, etc)

    @events = @events.to_a
  end

end

index.html.erb

<% params[:filters] ||= {} %>
<form class="form-inline">
    <fieldset>
        <legend>Filters</legend>
        
        <div class="pull-right">
            <input type="text" placeholder="zip" name="filters[zip]" value="<%= params[:filters][:zip] %>">
            <input type="submit" value="Apply">
        </div>

        <input type="hidden" name="filters[when]" value="<%= params[:filters][:when] || '' %>">
        <div class="btn-group">
            <%= link_to 'Past', events_url(filters: params[:filters].merge(when: 'past')), class: "btn btn-inverse #{'active' if params[:filters][:when] == 'past'}" %>
            <%= link_to 'Current', events_url(filters: params[:filters].merge(when: 'now')), class: "btn btn-inverse #{'active' if params[:filters][:when] == 'now'}" %>
            <%= link_to 'Future', events_url(filters: params[:filters].merge(when: 'future')), class: "btn btn-inverse #{'active' if params[:filters][:when] == 'future'}" %>
            <%= link_to 'All', events_url(filters: params[:filters].merge(when: nil)), class: "btn btn-inverse #{'active' if params[:filters][:when].blank?}" %>
        </div>

        <input type="hidden" name="filters[sort]" value="<%= params[:filters][:sort] || '' %>">
        <div class="btn-group">
            <%= link_to 'Newest First', events_url(filters: params[:filters].merge(sort: '-start_time')), class: "btn btn-inverse #{'active' if params[:filters][:sort] == '-start_time'}" %>
            <%= link_to 'Oldest First', events_url(filters: params[:filters].merge(sort: 'start_time')), class: "btn btn-inverse #{'active' if params[:filters][:sort] == 'start_time'}" %>
        </div>
    </fieldset>
</form>

Thanks for your help on this; I got everything working. I had to modify the sort section to include the filter parameter.

if params[:filters][:sort].present?
# sort in reverse order if the sort param starts with a hyphen
# allows you to create links like ....&sort=name... or ....&sort=-name.... for reverse order by name
if params[:filters][:sort].start_with?('-')
sortby = params[:filters][:sort].sub(/^-/, '') + ' Desc'
logger.info sortby
# then add the sort param to the events query
@events = @events.order(sortby)
else
# default sort
@events = @events.order('StartDate')
end