how to use form to update the model stored in the session

rubyonrails-talk
1

hello:   I am building a shopping_cart.Before the user proceed to check out,i want the user to be able to modify the quantity for any cart_item,so there is a quantity update function which is a rails form in the cart page. 1. cart information are kept in the session,cart are made of some cart_items,every cart_item has title,price,quantity...attributes. 2. cart_item is not stored in the database,but there is cart_item model,every cart_item object are made from the product object which has corresponding model and table in the database.    My problem: when i use form to update the quantity attributes for some cart_item,the corresponding method can not output the expected result, the quantity does not changed.Who can help me?The following are my codes: <%=form_tag(:action=>"quantity_update",:id=>cart_item)-%>      <%=text_field :cart_item,:quantity,"size" => 10 -%>      <%=submit_tag "recalculate"%>    <%=end_form_tag-%> def quantity_update     @cart=find_cart     #items is an array storing the cart_items     modified_item=@cart.items.find{|i|i==params[:id]}     if modified_item      index=@cart.items.index(modified_item)      modified_item.quantity=params[:cart_item][:quantity]      @cart.items[index]=modified_item      return @cart     end   end private def find_cart    session[:cart]||=Cart.new end

2

who can help me?

3

Guo Yangguang wrote:

who can help me?

Could it be that in

  modified_item=@cart.items.find{|i|i==params[:id]}

the i is an integer, whereas params[:id] is a string.

A simple guess.

Stephan