wrong attribute price calculation ?

I have zen cart 1.3.8 running on a local test site with WinXP and WAMP server (php v. 5.2.6 and mysql v. 4.1.22 and Apache 2.2.8). I have installed the Dual Pricing Module (v. 1.5)

There is a product with a base price of €2.30
I added two attribute options with the following settings (check boxes selection):

Option Name: Dimensions
Option Value: 8 X 10 cm
Prefix Price: + 0.0000

and

Option Name: Dimensions
Option Value: 10X12 cm
Prefix Price: + 5.0000

So, if I have understood well, I expect that when a customer checks the "8 X 10 cm" attribute, he/she will be charged €2.30, i.e. the base price itself. (regarding the net price of the product)
When I check both checkboxes (i.e. the customer orders both 8 X 10 cm and 10X12 cm attributes) I would expect that the charges are €2.30 for the 1st product and €7.30 for the 2nd product (i.e. 2.30 € which is the base price plus 5 € which is the attribute price). That makes 9.60 € sub-total.
Nevertheless, in the cart there is a 7.30 € sub-total only. There is only one product appearing with 7.30 € price, but both dimensions are written on the lower part of the cart.
I wonder if I have missed something in the logic of product attributes...

Go back and make this "radio buttons" instead of checkboxes - then only one can be selected.... if there are actually 3 items price by attributes and remove the 2.30 for that item and add it as an attribute also

and how do I set it up if I want the customer to have the capibility to select multiple attributes at the same time (i.e. use checkboxes), but each selected attribute is actually considered a whole product (e.g. if the customer selects 2 items via checkboxes that each corresponds to a version of the product with specific dimensions, the cart will show 2 products, product1 (8 X 10 cm) at 2.30 €, and product 2 (10X12 cm) at 7.30 € (2.30 base price plus 5.00 attribute price), giving a sum of 9.60 € (net price) just with one click on the "add to cart" button.

Do you allow purchase without the base item?
As in I only want the 10X12 cm product and not the 8 X 10 cm product

If so, then as stated, do not include the 2.30 price and make each selecteble via check box and price each appropriately as these is not now a 2.30 to be added upon

Do you allow purchase without the base item?

How do I do that ? I have searched in the manual but cannot find this option.
Also, in case each product version has a unique sku code, can I output this beside each version (i.e. attribute)?

How do I do that ? I have searched in the manual but cannot find this option.
Are you asking how to add a product that has no proce but is priced fully by attributes???

If so, then when entering/editing the product do not enter a price but select the "Product Priced by Attributes:" radio selector

Also, in case each product version has a unique sku code, can I output this beside each version (i.e. attribute)?
Not with default code as it is arranged to sell items with additions and not unique items/sku's in a single product.
You might get the "stock by attributes" 3rd party module by kurio and see what it might afford you.

I implemented your tip, but what I actually have, is thousands of products that most of them have a basic item and 2 or more versions of that basic item, that each has its own name, size, price, and model number.

All the versions along with the basic product share the same general description and maybe the same photo, but actually the multiple versions of these basic products are unique items with each one having the above characteristics.

Now, my client wants to display the basic product and below it, its multiple versions, on rows, each version with the model no, the name and price. Of course, each one of them must also have it's own weight as well, stored in the database for the correct shipping charge calculation.

Also, there are hundreds of products that are "individual", i.e. they dont have versions, but again they have all the above characteristics. These products are under the same parent subcategory with the products that have multiple versions.

The site visitor must be able to do a search by sku code either that code belongs to a basic product or to a product version,.
Also, there is another attribute - "drawing style", for which I also want to add a search feature to the site.

Now, if I use the attribute approach for the model numbers, I cannot store model numbers for each attribute with the current stock code. except including them in the attribute value (e.g. "<version name> - <version size> - <version model no>"), but that is not a "clean" solution, because the model number of the "individual" products and the model no of the versions will be stored in different fields/tables and will be probably different datatypes, a clumsy half-solution which might create more problems later, when the database has many products. There will still be a need for search in both fields if I did that.
Instead, I would like to have one unique field for the model no. of any item, either it is a basic product or a version.

From another thread of mine (http://www.zen-cart.com/forum/showthread.php?t=117926), someone suggested to me a subcategory organization approach, something I had in mind also (this approach arises from the fact that one cannot mix both categories and products under the same parent category):

What you might do is to make subcategories for all of the products, with some of them having only the one product.
Set admin > Configuration > Layout Settings > Skip 1-prod Categories to true, and clicking those products' subcat links will take you directly to the product.
It's functionally almost the same as having products and subcats in one category, though it is more labor-intensive in the backend. If there are not hundreds of products that will need this treatment, it sounds viable to me.

There are hundreds of products that will need this treatment, but I think this approach is more correct, database-wise, since the multiple versions of a basic product are not actually items with additions, but they are unique products themselves with unique, model no, price, names, sizes. In that case, (the subcategory approach) all the model numbers, would be stored in the default "Product Model" characteristic (provided by the stock code), and there would be need for only one attribute, the drawing-style.

Also, there would be need for adding code for search by model no. and by drawing style, but the data would be stored in a more clean way. The disadvantage of this method though, would be the "individual" products (without versions) that would have to be converted to subcategories with only one product contained within them. And these products might also be many hundreds, so it would be weird to have many products as subcategories and inside them the same product stored.

Taking into consideration all of the above, is there any module that would cover all these issues (or the next zen cart version), and if not, what would be the best approach ? (attributes or sub-categories, or what ?)

I have some php, mysql, html experience and I can find my way through code, so I would appreciate any code tips that would help me to the above issues.
(I haven't stored any products, yet, I am just setting up the site, so I want to follow a correct approach from the start).
I really appreciate some help.

Taking into consideration all of the above, is there any module that would cover all these issues (or the next zen cart version), and if not, what would be the best approach ? (attributes or sub-categories, or what ?)

I have some php, mysql, html experience and I can find my way through code, so I would appreciate any code tips that would help me to the above issues.
(I haven't stored any products, yet, I am just setting up the site, so I want to follow a correct approach from the start).
You probably should install a test instance of ZenCart, make a DB backup, and then proceed to add a few of these items in different ways to see what they display like and your options.
And as stated get the stock by attributes module as it will offer other options.

If you mess it all up, just restore the DB backup and start again

Many subs with only one product makes for hard to shop experience

I am posting the Stock by Attributes v4.7a function description.

This add-on allows a store owner to set a stock value for each variant of a product. For example, if you have three sizes, large, medium and small, this module will allow you to keep track of all the different quantities. It will work for a virtually unlimited number of amount of attribute combinations. For example, if you offered cotton or polyester shirts in green, red or blue and small medium or large sizes, this add-on would allow you to enter and maintain a separate stock level for each of the 18 possible combinations.

I was wondering what that module have to do with my case that I have described in my lengthy post above. I don't care about keeping stock levels of different attribute combinations, but just to store sku numbers of all products, both those without variants and product-variants of basic products, as well as do search by sku number and by another attribute (drawing style).

Do you still recommend to go ahead and install it ?

My intention was to add the following in my previous post ...

In other words, I want to bind to a specific variant-size (which is one attribute) another attribute which is the sku number of the product variant that has that specific size.
e.g. basic product: flowerpot A with common description and a starting price and weight
variant 1: flower pot A - size 8x10 cm - sku no 123456 - price 23 $ - weight 0,5 kg
variant 2: flower pot A - size 10x15 cm - sku no 547325 - price 32 $ - weight 0,8 kg
................................................................................
and goes on........

All these product variants of flowerpot have one drawing style which will be another attribute. Search ability by both sku no and drawing style.

I was wondering what that module have to do with my case

my client wants to display the basic product and below it, its multiple versions, on rows, each version with the model no, the name and price.
You are looking for options that are not part of the default install and I was only offering alternatives for your review