rails ActionView::Template::Error: undefined method `id' for nil:NilClass のエラー

Question

Failure/Error: @user = User.find(current_user.id)

 NoMethodError:
   undefined method `id' for nil:NilClass

のエラーが解決できず詰まってしまいました。
解決法を教えてください

class BooksController < ApplicationController

  def show
    @book = Book.find(params[:id])
    @user = @book.user
    @book_new =Book.new
  end

  def index
    @user = User.find(current_user.id)
    @books = Book.all
    @book = Book.new
  end

  def create
    @book = Book.new(book_params)
    @book.user_id = current_user.id
    if @book.save
      redirect_to book_path(@book.id), notice: "You have created book successfully."
    else
      @user = User.find(current_user.id)
      @books = Book.where(user_id: @user.id)
      render 'users/show'
    end
  end

  def edit
    @book = Book.find(params[:id])
    if @book.user_id != current_user.id
      redirect_to books_path
    end
  end



  def update
    @book = Book.find(params[:id])
    if @book.update(book_params)
      redirect_to book_path(@book), notice: "You have updated book successfully."
    else
      render "books/edit"
    end
  end

  def destroy
    @book = Book.find(params[:id])
    @book.destoy
    redirect_to books_path
  end

  private

  def book_params
    params.require(:book).permit(:title, :body, :user_id)
  end
end

class UsersController < ApplicationController
  before_action :ensure_correct_user, only: [:update]

  def show
    @user = User.find(params[:id])
    @books = Book.where(user_id: @user.id)
    @book = Book.new
  end

  def index
    @user = User.find(current_user.id)
    @book = Book.new
    @users = User.all
  end

  def edit
    @user = User.find(params[:id])
    if params[:id].to_i != current_user.id
      redirect_to user_path(current_user.id)
    else 
      @user = User.find(current_user.id)
    end
  end

  def update
    @user = User.find(params[:id])
    if @user.update(user_params)
      redirect_to users_path(@user), notice: "You have updated user successfully."
    else
      render "show"
    end
  end

  private
  def user_params
    params.require(:user).permit(:name, :introduction, :profile_image)
  end

  def ensure_correct_user
    @user = User.find(params[:id])
    unless @user == current_user
      redirect_to user_path(current_user)
    end
  end
end

div class="row">
	<div class="col-xs-3">

		<h2>User info</h2>
		<%= render 'users/profile', user: @user %>

		<h2>New book</h2>
		<%= render 'books/newform', book: @book_new %>

	</div>

	<div class="col-xs-9">
		<h2>Book detail</h2>

		<table class="table">
			<% if @user.id == current_user.id %>
				<td>
					<%= link_to user_path(@user.id) do %>
						<%= attachment_image_tag @user, :profile_image, size:"40x40", class: "attachment user profile_image fallback", fallback: "no_image.jpg" %>
						<br>
						<%= @user.name %>
					<% end %>
				</td>
				<td><%= link_to @book.title, book_path %></td>
				<td><%= @book.body %></td>
				<td><%= link_to "Edit", edit_book_path(@book.id), class: "btn-sm btn-success edit_book_30617" %></td>
				<td><%= link_to "Destroy", book_path(@book.id), class: "btn-sm btn-danger destroy_book_30617", method: :delete, "data-confirm" => "本当に消しますか？" %></td>
			<% else %>
				<td>
					<%= link_to user_path(@user.id) do %>
						<%= attachment_image_tag @user, :profile_image, size:"40x40", class: "attachment user profile_image fallback", fallback: "no_image.jpg" %>
						<br>
						<%= @user.name %>
					<% end %>
				</td>
				<td><%= link_to @book.title, book_path %></td>
				<td><%= @book.body %></td>
			<% end %>
		</table>
	</div>

Answer 1

エラーメッセージのとおり、current_userがnil、つまりログアウト状態なだけではないでしょうか。

ログアウト状態でも当該ページを表示したいのであれば、「current_userがnil」という状態も想定してコードを書く必要があります。

Comments

[nnaodajklwe]

else　のところに条件を追加するって事ですか？
初心者ですみません

[maisumakun]

えっと、エラーはどのアクションで出ているのですか？