Using a partial class property inside LINQ statement

Question

I am trying to figure out the best way to do what I thought would be easy. I have a database model called Line that represents a line in an invoice.

It looks roughly

Answer 1

While not an answer to your subject, it may be an answer to your problem:

Since you seem willing to modify the database, why not create a new View in the database that is basically

create view TotalledLine as
select *, Total = (Price * Quantity)
from LineTable;

and then change your data model to use TotalledLine instead of LineTable?

After all, if your application needs Total, it isn't a stretch to think others might, and centralizing that type of calculation into the database is one reason for using a database.