c# - LINQ: Sequence contains no elements errror -


i trying solve error using linq. pulling xml node value using linq. problem facing when node not present in xml i'm getting sequence contains no elements error. tried using defaultifempty, singleordefault, , firstordefault. throws nullpointer exception. guess i'm not above methods correctly. how can use 1 of these solve poblem?

here's linq code i'm using.

var costnode6 = doc.root.descendants(ns + "serviceupgrades").single(c => (string)c.element(ns + "deliverytime") == "before 3:30 pm").element(ns + "total_cost");         var cost6 = (decimal)costnode6;

the ordefault methods return default value type if there no result, in case null. means when .element(ns + "total_cost") after call, you'll sequence contains no elements error if using single or null reference exception if using singleordefault.

what should pull call out , check result against null:

var deliverytime = doc.root.descendants(ns + "serviceupgrades")     .singleordefault(c => (string)c.element(ns + "deliverytime") == "before 3:30 pm"); if(deliverytime != null) {          var costnode6 = deliverytime.element(ns + "total_cost");     var cost6 = (decimal)costnode6;    }

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