DenaliHardtail DenaliHardtail - 4 months ago 81
C# Question

SQL Data Reader - handling Null column values

I'm using a SQLdatareader to build POCOs from a database. The code works except when it encounters a null value in the database. For example, if the FirstName column in the database contains a null value, an exception is thrown.

employee.FirstName = sqlreader.GetString(indexFirstName);


What is the best way to handle null values in this situation?

Answer

You need to check for IsDBNull:

if(!SqlReader.IsDBNull(indexFirstName))
{
  employee.FirstName = sqlreader.GetString(indexFirstName);
}

That's your only reliable way to detect and handle this situation.

I wrapped those things into extension methods and tend to return a default value if the column is indeed null:

public static string SafeGetString(this SqlDataReader reader, int colIndex)
{
   if(!reader.IsDBNull(colIndex))
       return reader.GetString(colIndex);
   return string.Empty;
}

Now you can call it like this:

employee.FirstName = SqlReader.SafeGetString(indexFirstName);

and you'll never have to worry about an exception or a null value again.