How to Add Devise Gem in rails app step by step guide:

first we need to understand what is Devise. In every application we need sign_in , sign_up functionality. Devise gem solve this problem to develop manually above functionality. 

result of this blog:

 

Getting starting with devise :

Add the following gem to gemfile

gem 'devise'

then run bundle 

Next you need to generate devise using below command:

rails generate devise:install

then run below commad , this commad willl create model.

rails generate devise user

if database is not created then create database using rake db:create and after rake db:migrate.

otherwise only migrate using rake db:migrate

You can copy Devise views (for customization) to your app by running:

rails g devise:views

And finally we succefully created on of the important feature of application. in which user should be able to sign in ,sign out ,sign up securely.