Ruby on Rails-搜索具有多个属性的记录

Question

I have written some code to search via a couple of attributes in all my Recipe records. The code works, but I would like some input on if it's ok, or how to make it better/faster.

I have a Recipe model with various attributes including name:string and ingredients:[array of integers] (postgres database). The ingredients are the ID's of a separate model Ingredient . This is a learning experience, I don't want to use any gems.

My form index.html.erb

<%= form_tag recipes_path, :method => 'get' do %>
  <p>
    <%= text_field_tag :search, params[:search] %>
    <%= collection_select( :ingredients, :ingredient_ids, Ingredient.all, :id, :name, {:include_blank => false, include_hidden: false}, { :multiple => true  } ) -%>
   <%= submit_tag "Search" %>
  </p>
<% end %>

recipes_controller.rb

 def index
    @recipes = Recipe.search(params[:search], params[:ingredients])
  end

recipe.rb

  def self.search(search, ids)
    array = []
    if search && !search.empty?
      meals = where('name ILIKE ?', "%#{search}%")
      meals.each do |meal|
        array.push(meal)
      end
      if ids && !ids.empty?
        ingredients(array, ids)
      else
        return array
      end
    elsif ids && !ids.empty?
      ingredients(all, ids)
    else
      all
    end
  end

  def self.ingredients(meals, ids)
    newarray = []
    if ids
      meals.each do |me|
        a = me.ingredients
        b = ids[:ingredient_ids].map(&:to_i)
        if (b - a).empty?
          newarray.push(me)
        end
      end
      return newarray
    else
      return meals
    end
  end

This works fine at the moment as I don't have many records, but I don't trust that it'll be very fast if I had hundreds or thousands of records. Any advice on improving things?

Answer 1

If you know you're going to be searching on one or more columns frequently, try adding a database-level index for those columns. Without an index, any search will be O(n) time where n is the number of records. However, if you use an index, a search will be O(log(n)) time, because with the data ordered by your search column, you can binary search through it.

Take a look at http://weblog.rubyonrails.org/2011/12/6/what-s-new-in-edge-rails-explain/ for more information at how to check if your query performance can be improved.

Two other things to consider performance-wise:

1) For your all condition, you might be returning waaaay more records than you want. You may want to consider using pagination (I know you mentioned no other gems, but there are some great gems for pagination out there).

2) If you do actually want to return a ton of records at once, consider using ActiveRecord's batching (I usually use #find_each) to ensure you don't load everything into memory at once and end up OOM-ing.