Question

I’m having problems trying to edit a model. I always end up getting as error

undefined method `model_name' for NilClass:Class

I’m using in the view:

<%= form_for(@book) do |f| %>

and on the controller:

 def edit
@title = "Edit Book"
 end

def update
@book = Book.find(params[:id])
if @book.update_attributes(params[:book])
  flash[:success] = "Book Updated"
  redirect_to @book
else
  @title = "Edit Book"
  render 'edit_book_path(@book)'
end
end

Answer 1

You have to initialize the @book variable in the ‘edit’ action. As you can see from your view:

<%= form_for(@book) do |f| %>

the @book variable is used for rendering the form. Thus:

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

is needed in edit method.