How to create form that switches between instances of a model?

Question

I have a model, Product, and on the show view for this model, I want to have a select box for the user to be able to view a different Product. So, if a user's looking at the "Product 1" page, they can select "Product 2" from the select box and view that product.

Here's the code I'm using to create this select box:

<%= form_tag({:controller => "products", :action => "show"}, :method => :get) do %>
<%= select_tag :product_id, options_from_collection_for_select(Product.all, :id, :title) %>
<%= submit_tag 'Go' %>

But this doesn't work. I can choose a different product, and click Go, but it just goes to the same product, not the one I selected in the box.

What am I doing wrong here?

Basically, I'm trying to use a select box instead of something like this:

<% Product.all.each do |p| %>
    <%= link_to p.title, p %>
<% end %>

Here's what I have for my show action in the controller:

@product = Product.find(params[:id])
    rescue ActiveRecord::RecordNotFound
    flash[:alert] = 'The product you were looking for could not be found'
    redirect_to products_path

Answer 1

If you can post your code on the ProductsController for Show, it would clarify things more.

The id you want to use for "showing" the right product is passed by params[:product_id]. So you should be using that in your ProductsController

Answer 2

well a simple way would be to check if the params[:product_id] was passed by your form, if it is then use that instead of params[:id] basically:

if params[:product_id]
   @product = Product.find(params[:product_id])
else
   @product = Product.find(params[:id])
end