Question

Howsit!

I encounter an error when i get a null value in my datareader.

public List<Complaint> View_all_complaints()
{
    csDAL objdal= new csDAL();
    List<Complaint> oblcomplist=new List<Complaint>();

    using( IDataReader dr=objdal.executespreturndr("View_all_complaints"))
    {
        while (dr.Read())
        {
            Complaint objcomp= new Complaint();
            populate_reader(dr,objcomp);
            oblcomplist.Add(objcomp);
        }
    }
    return oblcomplist;
}

public void populate_reader(IDataReader dr, Complaint objcomp)
{
    objcomp.ref_num = dr.GetString(0);
    objcomp.type = dr.GetString(1);
    objcomp.desc = dr.GetString(2);
    objcomp.date = dr.GetDateTime(3);
    objcomp.housenum = dr.GetInt32(4);
    objcomp.streetnum = dr.GetInt32(5);
    objcomp.status = dr.GetString(6);
    objcomp.priority = dr.GetString(7);
    objcomp.cid = dr.GetInt32(8);
    if (!dr.IsDBNull(9))
    {
        objcomp.resolved_date = dr.GetDateTime(9);
    }
}

in sql resolved date allows null values, this is so because only when a complaint has been resolved , it must reflect that date otherwise it should be null.

if dr.getdatetime(9) is null then it must just set a string saying “Not Resolved”

please help!

Answer 1

You haven’t shown what your Complaint type looks like, but basically you’ll want to make sure that its resolved_date is of type DateTime? aka Nullable<DateTime>. That allows you to model a missing value elegantly.

As for displaying it – you haven’t shown anything about where you display the data, but you’d want something like:

string text = complaint.ResolvedDate.HasValue ? complaint.ResolvedDate.ToString()
                                              : "Not Resolved";

(I’ve changed this to use a property with the idiomatic name at the same time…)