Question

Is it possible to ignore Where clause if Sessions.Current.AdminProductId is null? I would like to optimize code below into one line of code.

if (Sessions.Current.AdminProductId == null)
  gvUsers.DataSource = DataAccess.Instance.Users;
else
  gvUsers.DataSource = DataAccess.Instance.Users.Where(p => p.Orders.Any(o => o.ProductId == Sessions.Current.AdminProductId));

Answer 1

You just need to add the null check in the where clause like this:

 gvUsers.DataSource = DataAccess.Instance.Users.Where(p => (Sessions.Current.AdminProductId == null) || (Sessions.Current.AdminProductId != null && p.Orders.Any(o => o.ProductId == Sessions.Current.AdminProductId)));