Question

I have the following Linq to Sql:

var subscribers = (from s in dataContext.Employees
                               where s.RowType == "Edit"
                               select new SubscriberExportData
                                          {
                                              ID = s.ID.ToString(),
                                              GroupNum = s.GroupNumber,
                                              DivisionNum = s.DivisionNumber,
                                              HireDate = s.HireDate != null ? Convert.ToDateTime(s.HireDate).ToShortDateString() : string.Empty,
                                              EffDate = s.EffectiveDate != null ? Convert.ToDateTime(s.EffectiveDate).ToShortDateString() : string.Empty
                                           }

Essentially, if the date value is not null then convert them to short date format. But I am getting the following error:

System.InvalidOperationException was unhandled
Message=Could not translate expression ‘Table(Employee).Where(s => (s.RowType == “Edit”)).Select(s => new SubscriberExportData() { HireDate = IIF((s.HireDate != null), ToDateTime(Convert(s.HireDate)).ToShortDateString(), Invoke(value(System.Func`1[System.String]))), EffDate = IIF((s.EffectiveDate != null), ToDateTime(Convert(s.EffectiveDate)).ToShortDateString)’ into SQL and could not treat it as a local expression.
Source=System.Data.Linq

Please let me know how to resolve it.

Answer 1

You can split the query into two, the first being operations that sql understands and the second being the string conversions that will be performed locally

var list = (from s in dataContext.Employees
                           where s.RowType == "Edit"
                           select new
                                      {
                                          s.ID 
                                          s.GroupNumber,
                                          s.DivisionNumber,
                                          s.HireDate 
                                          s.EffectiveDate  
                                       }).ToList();

var subscribers = (from s in list
                           select new SubscriberExportData
                                      {
                                          ID = s.ID.ToString(),
                                          GroupNum = s.GroupNumber,
                                          DivisionNum = s.DivisionNumber,
                                          HireDate = s.HireDate != null ? Convert.ToDateTime(s.HireDate).ToShortDateString() : string.Empty,
                                          EffDate = s.EffectiveDate != null ? Convert.ToDateTime(s.EffectiveDate).ToShortDateString() : string.Empty
                                       }