How to check if the product don't exist?

I have a table records "TableRecordsProducts" that show some info about the products that belong to a customer quotation. For example to show the description in the table records is like:


TableRecordsProducts.List.Current.QUOTATION_CUSTOMER.Product_Description

A quotation can have multiple products, so this TableRecordsProducts can have multiple products. For each record (product) in the TableRecordsProducts there is a button that when is clicked expands that row to show the proposed product for each product. There is an action associated to this button "ExpandRow". In the "ExpandRow" action I have an assign:

GetQuotationProducts.List = TableRecordsProducts.List. 

And after this assign there is an ajax refresh to update the TableRecordsProducts. Its working.

But a quotation can have products that don´t exist, in this case the product id is 0, so for each record, when a proposed product doesnt exist, when the "ExpandRow" button is clicked is necessary to execute some logic instead of expanding the row to show the proposed product for that product, for now I just want to show a feedback message when the product id is 0 (when the product don´t exist).

But Im not understanding how to vo verify for each record in the "TableRecordsProducts" when the user click in the expand button if the product id of the current row os 0 or not to show the feedback message. Do you know how to achieve that?

Might be helpful if you can include screenshots of the UI and the current flow for the ExpandRow action. Hard to fully understand what you're wanting to do here with just the information you've provided.