I try to learn the has_and_belongs_to_many relationship between my 2 fresh new and simple models Product and Author, where a Product can have many authors and where author can have a lots of products.
I wrote this :
class Author < ActiveRecord::Base
  has_and_belongs_to_many :products
end
class Product < ActiveRecord::Base
  has_and_belongs_to_many :authors
end
In the partial form of view for the products, I have :
<p>Products</p>
<%= collection_select(:product, :author_ids, @authors, :id, :name, :prompt => " ",  :multiple => true) %>
but when I hit the update button, I get this strange message I can't resolve myself :
NoMethodError in ProductsController#update
undefined method `reject' for "1":String
Rails.root: /home/stephane/www/HABTM
Application Trace | Framework Trace | Full Trace
app/controllers/products_controller.rb:63:in block in update'
app/controllers/products_controller.rb:62:inupdate'
Request
Parameters:
{"utf8"="✓",
 "_method"="put",
 "authenticity_token"="2GlTssOFjTVZ9BikrIFgx22cdTOIJuAB70liYhhLf+4=",
 "product"={"title"="Le trésor des Templiers",
 "original_title"="",
 "number"="1",
 "added_by"="",
 "author_ids"="1"},
 "commit"="Update Product",
 "id"="1"}
What's wrong ? Is there a problem with :product_ids... I saw on internet I had to pu a "s" but I'm not sure of what it represents....
How can I link the table authors_products to the key which is given back by the drop-down menu ? (here "author_ids"="1")
Thx !