I get a row from table and some field of this row are null. How can I get these fields with SqlDataReader?
//so_type , so_read are null able
while (reader.Read())
{
s.id = (Int64)reader["so_id"];
s.senderid = (Int64)reader["so_senderid"];
s.body = (string)reader["so_body"];
s.date = (string)reader["so_date"];
s.isread = (bool)reader["so_read"];
s.type = (int)reader["so_type"];
}
You can take advantage of C# generics to write a helper method which extracts the value or default for each column that can be null.
private static T GetValue<T>(object value)
{
return value == DBNull.Value ? default(T) : (T) value;
}
while (reader.Read())
{
s.id = GetValue<long>(reader["so_id"]);
s.senderid = GetValue<long>(reader["so_senderid"]);
s.body = GetValue<string>(reader["so_body"]);
s.date = GetValue<string>(reader["so_date"]);
s.isread = GetValue<bool>(reader["so_read"]);
s.type = GetValue<int>(reader["so_type"]);
}
This also assumes the value is already the correct type.
A more type safe implementation would be:
private static T GetValue<T>(object value)
{
return value == DBNull.Value
? default(T)
: (T) Convert.ChangeType(value, typeof(T));
}
You can use the IsDBNull method. Something like that:
int ordinal_so_type=reader.GetOrdinal("so_type");
//...
while(reader.Read()==true)
{
//reading other columns here
if (reader.IsDBNull(ordinal_so_type)==false)
{
s.type=reader.GetInt32(ordinal_so_type);
}
else
{
//do whatever you like if the so_type column is null
}
}
