environment

・ Rails 5 -Implemented login function using device

Prevent users who are not logged in from going to the post edit screen

Change the display screen depending on whether you are logged in or not

`view.rb`


<% if user_signed_in? %>

If you are not logged in, jump to the login screen

`controller.rb`


before_action :authenticate_user!

Prevent other users from going to the post edit screen

If you write it only on the view side, you can change it by hitting the url directly, so write it on the controller side as well.

`controller.rb`


@book = Book.find(params[:id])
  if @book.user == current_user
    render "edit"
  else
    redirect_to books_path
  end

`view.rb`


<% if @book.user == current_user %>
　　〜〜〜〜〜
<% end %>

Different way

`controller.rb`


  before_action :ensure_correct_user, only: [:edit, :update]

  def ensure_correct_user
    unless @user == current_user
      redirect_to user_path(current_user)
    end
  end

if statement → If the evaluation is true(true)If so, do ○○ unless statement → If the evaluation is false(false)If so, do ○○

Finally

Since the author is a beginner, I think there are some mistakes and lack of explanation. I would appreciate it if you could point out in that case.

References

https://qiita.com/tobita0000/items/866de191635e6d74e392