Question

A model named ‘book’ with attributes ‘name’ and ‘id’ is given. How can i use this collection select to call the show-action of a certain book? The one code mentioned below returns the following error message:

Couldn’t find Book with ID=book_id

<% form_tag(book_path(:book_id)), :method => :get  do %>   <p>   <%= label(:book, :id, 'Show Book:') %>     <%= @books = Books.find(:all, :order => :name)       collection_select(:book, :id, @books, :id, :name)    %>    </p>   <p>   <%= submit_tag 'Go' %>   </p> <% end %> 

Answer 1

book_path is generated once only, for the form tag itself. It won’t be updated whenever your selection changes.

When you submit that form, it’s going to request the following URL:

/books/book_id?book[id]=5 

Since your book_path thinks book_id is the ID number you wanted, it tries to look that up. You could do what you want you by changing the code in your controller from:

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

to:

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

But it kind of smells bad so be warned.