Checking for nulls in Linq Query

Question

I have a dataset on which I'm making a linq query.

var results = dtWorkCenters.AsEnumerable()
            .Where(x => x.Field<string>("Work_Center") == theWorkCenter && x.Field<string>("Job") == theJob)
            .Select(x => new
                {
                    Operation = x.Field<string>("Job_Operation"),
                    WorkDate = x.Field<DateTime>("Work_Date"),
                    Employee = x.Field<string>("Employee"),
                    SetupHours = x.Field<double>("Act_Setup_Hrs"),
                    SetupDollars = x.Field<double>("Act_Labor_Dollars"),
                    RunHours = x.Field<double>("Act_Run_Hrs"),
                    RunDollars = x.Field<double>("Act_Labor_Dollars")
                });

The field Job_Operation is a string int the database, but may contain a null value. The above syntax fails on the null values. How do I protect against nulls in the data?

Answer 1

I think the issue you are having with null values may be a result of trying to set the value type (DateTime and double) properties (WorkDate, SetupHours, etc.) to null.

If that is the case, try specifying Nullable<DateTime> and Nullable<double> as the generic Field type by using DateTime? and double? in your calls to x.Field<T> like so:

var results = dtWorkCenters.AsEnumerable()
                  .Where(x => x.Field<string>("Work_Center") == theWorkCenter 
                                   && x.Field<string>("Job") == theJob)
                  .Select(x => new
                               {
                                    Operation = x.Field<string>("Job_Operation"),
                                    WorkDate = x.Field<DateTime?>("Work_Date"),
                                    Employee = x.Field<string>("Employee"),
                                    SetupHours = x.Field<double?>("Act_Setup_Hrs"),
                                    SetupDollars = x.Field<double?>("Act_Labor_Dollars"),
                                    RunHours = x.Field<double?>("Act_Run_Hrs"),
                                    RunDollars = x.Field<double?>("Act_Labor_Dollars")
                               });