c# - Building an object that might contains null ref-CodePudding

i'm trying to build an object with below attribute

    public class data
    {
        public string Ref{ get; set; }
        public string Number { get; set; }
        public string Type{ get; set; }
        public string? Origin{ get; set; }

    };

Thing is that : ref / Number / Type, i'll be sure to find those data in my XML file, but Origin might be null in some cases.

Below code is looped via some elt in a XML file, some times we can find origin in a collection of subelement, sometimes origin cannot be found since there is no subelement matching condition.

How can I handle this null exception while still building my object ? The goal is to have an Origin = "" if it cannot be found.

           containerData.Add(new dataContainer()
            {
                Ref= elt.Descendants(ns   "Ref")
                      .FirstOrDefault()
                      .Value,

                Number = elt.Descendants(ns "Number")
                         .FirstOrDefault()
                         .Value,

                Type = elt.Descendants(ns   "Type")
                         .FirstOrDefault()
                         .Value,

                Origin = subElement.Where(x => x.Element(ns   "Name").Value == "Origin")
                                .Select(x => x.Element(ns   "Value"))
                                .SingleOrDefault()
                                .Value,

            });

trying to get Origin nullable type, but object still throwing me exception when building.

CodePudding user response：

.SingleOrDefault() may return null, so you may guard against that with .SingleOrDefault()?.Value (=> Only access Value if not null).

This leaves you with a value or null. If you want to have an empty string in that case (if null), you can use .SingleOrDefault()?.Value ?? "".

For reference: