過濾空值

Question

var invoice = (from i in Catalog.Invoices 
        where (i.Id == invoiceId) 
        select i) 
        .Include(i => i.Appointment.Service) 
        .Include(i => i.Appointment.Allocations.Select(a => a.Service)) 
        .Include(i => i.Appointment.Allocations.Select(e => e.Employee)) 
        .FirstOrDefault(); 

var inv = invoice.Appointment.Allocations.Select(e => e.Employee); 

我的問題：如何將空值從上面的查詢過濾器？

Answer 1

您應該在查詢中添加Where子句以過濾出null值。

無論是後Select：

var inv = invoice.Appointment.Allocations.Select(e => e.Employee).Where(e => e != null); 

或Select前：

var inv = invoice.Appointment.Allocations.Where(e => e.Employee != null).Select(e => e.Employee);