ActionController::UrlGenerationError in Books#indexを解決できない

Question

No route matches {:action=>"show", :controller=>"books", :id=>nil}, missing required keys: [:id]　とエラーが出てしまいます。

<tbody>
    <% @books.each do |book| %>
      <tr>
        <td><%= book.title %></td>
        <td><%= book.body %></td>
        <td><%= link_to 'Show', book_path(book), class: "show_#{@book.id}" %></td>
        <td><%= link_to 'Edit', edit_book_path, class: "edit_#{@book.id}" %></td>　←エラー`
        <td><%= link_to 'Destroy', book_path(book), method: :delete, data: { confirm: 'Are you sure?' }, class: "destroy_#{@book.id}" %></td>
      </tr>
    <% end %>
  </tbody>
</table>

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

  def create
    @book = Book.new(book_params)
    if @book.save
      redirect_to book_path(@book), notice: "successfully created book!"
    else
      render 'index'
    end
  end

  def edit
    @book = Book.find(params[:id])
  end

  def update
    if @book.update()
      redirect_to book_path(@book), notice: "successfully updated book!"
    else
      render 'edit'
    end
  end

  def destroy
  	@book.destroy
  	redirect_to books_path, notice: "successfully delete book!"
  end

  private

  def set_book
    @book = Book.find(params[:id])
  end

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

Answer 1

エラーメッセージのとおりです。edit_book_pathには編集対象を指定する必要があります。

edit_book_path(id)あるいはedit_book_path(Bookのモデルオブジェクト)の形で指定してください。