You can use sessions to store data between requests. To use sessions use the session helper. Example:

class PostsController < ApplicationController
  def index
    session[:current_time] =
    render json: {message: "set some data in the session"}

  def show
    # session data from previous show request
    puts "session[:current_time] #{session[:current_time]}"
    render json: session

Session Storage Backends Configuration

The default cookies session storage can be configured and changed.

Cookies Storage

Here’s an example configuring the default cookie storage backend.

Jets.application.configure do
  config.session.options = { key: 'rack.session',
                             domain: '',
                             path: '/',
                             expire_after: 2592000,
                             secret: ENV['SECRET_KEY_BASE'],
                             old_secret: ENV['SECRET_KEY_BASE_OLD'] }

Note, you can also configure the SECRET_KEY_BASE with your .env files. If you’ve generated a Jets project after version 1.1.0 then a random SECRET_KEY_BASE value was already generated in your .env. You can use jets secret also to generate a new secret value.

Memcached Storage

You can use Memcached storage for your sessions. Memcached support is provided with the dalli and connection_pool gems. You will need to add them to your Gemfile:


gem "dalli"
gem "connection_pool"

You also need to require "rack/session/dalli" to add the rack session adapter. Example:


require "rack/session/dalli"

Jets.application.configure do
  # ... = Rack::Session::Dalli
  config.session.options = { memcache_server: "localhost:11211",
                             pool_size: 10 }

Sessions Best Practices

It is best practice to store reference data like a database record id in session and look up the record in the application code. This keeps session data size smaller. Also, the code is more robust to changes when the data structure changes later. For example, the structure can change when a column is added to the table. The default session storage is cookies. Cookies are limited to 4k of data. So keep the session data underneath this limit for cookies.

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