[RUBY] [Rails] Temporary retention of data by session


session is used when moving to the transition destination while holding data in "wizard format" etc.

table of contents

  1. About the session
  2. Implementation example
  3. Finally

1. About the session

A session is a mechanism for temporarily storing information. In Rails, a session stores data in an object called session in the form of a hash.

For example, suppose a site where the page changes when you register as a member. In this case, it is necessary to temporarily store the information entered using the session in the session, move to the next page, and expand it there.

2 Implementation example


As a premise, it is assumed that member information is saved while transitioning pages using devise.

Development environment

ruby 2.6.5 rails 6.0.0 devise 4.7.3

2.1 Data retention

Let's implement it!


class Users::RegistrationsController < Devise::RegistrationsController

  def new
    @user = User.new

  def create
    @user = User.new(sign_up_params)
      unless @user.valid?
        render :new and return
    session["devise.regist_data"] = {user: @user.attributes}
    @address = @user.build_address
    render "new_address"

I have written various other things, but I will pay attention to session.

session["devise.regist_data"] = {user: @user.attributes} 

{user: @ user.attributes} uses the attributes method to format the data when you want session to hold information in the form of a hash object.

In other words, the attributed @user data is in the session in a hashed state. Now, the input information is assigned to session ["devise.regist_data"] and it is in the retained state.

2.2 Deploy

Next, the page is transitioned and expanded while retaining the data.


class Users::RegistrationsController < Devise::RegistrationsController

 def create_address
    @user = User.new(session["devise.regist_data"]["user"])
    @address = Address.new(useraddress_params)
      if @address.valid?
          sign_in(:user, @user)
        render "new_address"

This is also described in various ways, but pay attention to @user at the top.

@user = User.new(session["devise.regist_data"]["user"])

Describes session ["devise.regist_data"] ["user"]. If you have data with {user: 〇〇}, you need to use ["user"]. Also, since session contains information in an array, you can also have information as follows. session["devise.regist_data"] = {user: @user.attributes, address: @user.address}

With this, session can be expanded on the transition destination page and assigned to @user.

After that, you can save using the data assigned to @user.


This time, I introduced how to use session when using devise in "wizard format".


I am a beginner in programming, but I am posting an article in the hope that it will help people who are similarly troubled. See you next time ~

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