Hello, 

I would like to restrict the number of BoM that can be created per product.

I want to do this so people will be able to create a BoM but only if the BoM didn't exist yet. 

We don't use variant so we don't need more than one BoM per product and we don't want to either (to make data management as simple as possible). 

I tried to make a Record Rules, with this code : 

[("product.template.bom_count", "

But I have an error : "

ValueError: Invalid field mrp.bom.product in leaf ('product.template.bom_count', '

If someone have a solution...
Thank you