How to avoid to a customer to buy a product without the model was checked?

[Oredayo]

Hi,
I am looking for information on how to avoid to a customer to buy a product without the model was checked?

For exemple: Presently, if a product has two sizes and the customer doesn't check which size he wants before clicking "add this to my cart", then the default product is added.

Is there a way to require the customer to check the size before he can proceed to "add this to my cart"?

Thank you in advance.

[Ajeh]

On the Option Values add an additional one such as:
Select One Below ...
Sort Order: 0
Default: YES
Display Only: YES

and this will require the customer to make a valid choice ...

[Oredayo]

Thank you Ajeh.

I watched in the "Option controller" and the "Option Values" and I don't see where to add:
"Select One Below ...
Sort Order: 0
Default: YES
Display Only: YES".

Could you please give me a little more details about how to do that?

Thank you very much.

[Ajeh]

As an example, in the Option Value Manager ...

Option Name: Color
Option Value: Select One Below ...
Default Sort Order: 0

Then go to your Product in the Attributes Controller and add the Attribute for:

Option Name: Color
Option Value: Select One Below ...
Sort Order: 0
Default: YES
Display Only: YES

Now when you go to the Product on the Store you will see this new Option Value: Select One Below ... as the pre-selected Attribute Option Value ... but unless the Customer picks a different choice, the Product cannot be added to the shopping cart ...

[Oredayo]

Thank you Ajeh. It works!

As I didn't need "Select One Below ..." I just checked the following "Attribute Flags":
- Default Attribute to be Marked Selected: YES

Do you know if there is a way to change the Default Attribute to be Marked Selected to YES for all products?

I watched in the "Product Type Info Page Layout options :: Product - General" to change it to:
"PRODUCT Attribute is Default - Default 1"

Unfortunately it will work only for the futur products I will insert to the catalog.

[Ajeh]

Not without knowing a great deal about your Products and Attributes ...