Why use Redis? Hitting kredis is much cheaper than hitting a relational database. By storing high-frequency data on Redis we save resources.

Wtf Kredis? Kredis makes using Redis easier in Rails, and most importantly helps to associate Redis object with Rails Models.

Previously I wrote about “Recently visited pages with Kredis”

Recent search history” is a very similar feature in terms of implementation.

Feature description:

  • whenever a user submits a search form, the search query is saved in redis
  • display the users last 5 search queries


  • scaffold Posts title:string
  • Authentication, current_user


First, associate a Redis entity of kredis_unique_list with the user.rb model:

# app/models/user.rb
class User < ApplicationRecord
  kredis_unique_list :recent_searches, limit: 5

Add a search form:

# app/views/posts/index.html.erb
<%= form_with url: posts_path do |form| %>
  <%= form.text_field :query %>
  <%= form.submit %>
<% end %>

When there search form is submitted, save the search params to current_user.recent_searches. prepend will add it at the top of the list:

# app/controllers/posts_controller.rb
def index
  @posts = if params[:query].present?
            Post.where(name: params[:query])
            current_user.recent_searches.prepend(params[:query]) if params[:query].present?

Display a list of clickable recent searches:

# app/views/users/_recently_searches.html.erb
<% current_user.recent_searches.elements.each do |query| %>
  <%= link_to query, posts_path(query:) %>
<% end %>

That’s it!