Rails Slug Filtering

restaurants_controller.rb

# Set up a /slug/ route to your #index in routes.rb
# get '/search/:slug', to: 'restaurants#index'

class RestaurantsController < ApplicationController
  def index
    if params[:slug]
      lookup = SlugLookupService.new(params[:slug])
      lookup.perform
      category = lookup.category
      redirect_to restaurants_path unless category
    end
    query = params[:q].presence || "*" # elastic search needs a default 'get all' query
    @restaurants = RestaurantSearchService.new(category || nil, query, params).perform
  end
end

slug_lookup_service.rb

# Dictionary is a PORO (plain ruby class)
# that contains an hash like structure:
# { "slug-name" => { id: 1, text: "category_name"} }
# and some util method to order terms and do internal searches
# which will allow to have more complex slugging rules

class SlugLookupService
  attr_reader :category

  def initialize(slug)
    @slug = slug
    @dictionary = Dictionary.new
    @category = nil
  end

  def perform
    lookup_slug
  end

  private

  def lookup_slug
    @dictionary.ordered_terms.each_with_index do |term, index|
      if @slug == term
        @category = @dictionary.text(term)
      end
    end
  end
end