take this linq into consideration:
list.Where(sil => sil.XML.Element("ticket") != null && sil.XML.Element("ticket").Attribute("id").Value == smsRequestIn.TicketID)
if the "ticket" element is not null it searches for it twice and hence is not very effective. Is there a way to use some sort of variables within the linq expression so I can reference the variable instead of doing a double search for the "ticket" element or is linq intelligent enough to not do a double search?
In LINQ Expression syntax you'd use let like this:
from sil in list
let ticket = sil.XML.Element("ticket")
where ticket != null && ticket.Attribute("id").Value == smsRequestIn.TicketID
select sil;
To replicate let using extension methods, you need to use Select and an anonymous type like so
list.Select(anon => new { ticket = anon.XML.Element("ticket"), anon })
.Where(sil => sil.ticket != null && sil.ticket.Attribute("id").Value == smsRequestIn.TicketID)
.Select(o=>o.anon);
Which is abundantly less clear.
I'd rewrite your query to the following:
var result = from sil in list
let element = sil.XML.Element("ticket")
where element != null &&
element.Attribute("id").Value == smsRequestIn.TicketID
select sil;
You can do something like this:
Func<SilClass,bool> filter = sil =>
{
XElement e = sil.XML.Element("ticket");
return e != null && e.Attribute("id").Value == smsRequestIn.TicketID);
};
list.Where(filter);
but in this case I think you really benefit in using query syntax like other answers have suggested. It's much more clear.
