Ubercart

I just want to add that this is a fairly important feature, especially for apparel shops.

Example: If I have t-shirt designs and I want to sell shirts...I want to sell shirts by the design (not the article of clothing).

The product selection process would go like this:

1. Design selection
2. Attribute: Male or Female?
3. If Female, display female choices (ex: Ladies Scoop Neck T, Ladies Crewneck T, etc).
If Male, display male choices (ex: Men's Beefy Tee, Long Sleeve T-Shirt, etc)
4. If we choose "Mens" then "Long Sleeve T-Shirt" we would have a 3rd attribute field that asks us for size (S, M, L, XL, XXL, etc).
5. And again, from there, we might be able to choose from different colors (or choose colors first, then size)

The reasoning behind this is that some styles only have certain sizes.

An excellent example of this functionality can be found here: http://www.tshirthell.com/funny-shirts/talk-nerdy-to-me/?fdo=n (not a drupal site, but excellent at selling shirts).

So what's the best way to implement this functionality?

1. After we create our generic attribute sets, we should be able to create another object called an "attribute tree."
2. Attribute trees allow you to assign conditional attribute sets to EACH option within the parent attribute set. Once an attribute tree is created and saved, it will be available to use with any products.
3. An important ancillary feature would be the ability to mass-edit particular taxonomies inside our catalogues with these attribute trees (or perhaps just simple attribute groups).

And here is how I imagine the workflow:

1. Create attribute sets as usual:
a. Style (Men's Tshirt, Women's V-neck, toddler's bib)
b. Color Sets (Black), (Black, Red, Blue, White) (Tan/Blue, Taupe/Purple, Beige/Brown) etc.
b. Size sets: (women's v-neck sizes: S, M, L) (Men's T-Shirt Sizes: S, M, L, XL, XXL, XXXL), (Toddler Bibs: XS, S, M) etc...NOTE: these size sets are each distinctive attribute sets

2. Once my sets have been created, I can then create an attribute tree:
a. Assign a color set to each style.
b. Assign a size set to each color underneath the style set (yes, in a hierarchical fashion). (NOTE: I envision being able to even assign existing attribute trees (and not just attribute sets) to options as well)
c. Repeat for EVERY attribute option within the tree.
d. Save this attribute tree with a unique name.

3. That's it. Assign the previously created attribute tree to a product just like normal attributes.

4. When a user selects a style, they will then see the correct color set, and when they select a color, they will then see the correct size set (or however the store admin set it up).

I hope this sort of clarifies what we are asking for and how one might achieve it in theory...

I wrote a module which applies this sort of relationship defining and trimming logic to cck select fields for cck content types. It could probably be translated to select field attribute options for ubercart attributes. http://drupal.org/project/option_trim

It would need slimmed down and adjusted for UC, but it might be somewhere to start for those with some drupal/ubercart/jquery chops or if someone wants to sponsor a contrib, PM me and I could look at coding it up.