The admin form for creating new products do not detect that you have selected a category.

[adrianmcli]

If you tried to create a new product using the admin/products creation page, you will run into an error where it tells you that you cannot be submitting a product with a blank category (even if you actually did choose a category).

Line 38 from app/views/admin/products/new.html.erb reads:

<%= form.select :category, options_from_collection_for_select...

When it should read:

<%= form.select :category_id, options_from_collection_for_select...

This is because the app is expecting :category_id to be passed through.