Question

I have a LINQ statement where I’d like to merge in the First address with the Nickname of ‘Me’.

using (var ctx = new DataEntities()) {   return from c in ctx.Customers.Include('Addresses')          let m = from a in c.Addresses where a.Nickname == 'Me' select a          where m.Any()          select new          {            Id = c.CustomerId,            m.First().Name,            m.First().Address1,            m.First().Address2,            m.First().City,            m.First().State,            m.First().Zip,            m.First().Email,            m.First().PhoneNumber          }; } 

I’m wondering:

1. Is it going to hurt performance if I call First multiple times like this?
2. Is there an better LINQ statement for this?
3. Just also realized, Do I need to .Include(‘Addresses’)?

Answer 1

For LINQ to SQL, EF, etc, it probably won’t matter – it is entirely possible that the TSQL translation will make it identical anyway. Of course, you can profile to be sure ;-p

But for LINQ-to-Objects (which is very literal) it will. You can improve this by using let:

return from c in ctx.Customers.Include('Addresses')      let m = from a in c.Addresses where a.Nickname == 'Me' select a      where m.Any()      let first = m.First()      select new      {        Id = c.CustomerId,        first.Name,        first.Address1,        ...        first.PhoneNumber      };