Nullable GUID

Question

In my database, in one of the table I have a GUID column with allow nulls. I have a method with a Guid? parameter that inserts a new data row in the table. However when I s

Answer 1

same as Greg Beech's answer

myNewRow.myGuidColumn = (object)myGuid ?? DBNull.Value

Answer 2

If you are into extension methods...

/// <summary>
/// Returns nullable Guid (Guid?) value if not null or Guid.Empty, otherwise returns DBNull.Value
/// </summary>
public static object GetValueOrDBNull(this Guid? aGuid)
{
  return (!aGuid.IsNullOrEmpty()) ? (object)aGuid : DBNull.Value;
}

/// <summary>
/// Determines if a nullable Guid (Guid?) is null or Guid.Empty
/// </summary>
public static bool IsNullOrEmpty(this Guid? aGuid)
{
  return (!aGuid.HasValue || aGuid.Value == Guid.Empty);
}

Then you could say: myNewRow.myGuidColumn = myGuid.GetValueOrDBNull();

NOTE: This will insert null when myGuid == Guid.Empty, you could easily tweak the method if you want to allow empty Guids in your column.

Answer 3

You have to cast null to a nullable Guid, this how it worked for me :

myRecord.myGuidCol = (myGuid == null) ? (Guid?)null : myGuid.Value

Answer 4

or:

    internal static T CastTo<T>(object value)
    {
        return value != DBNull.Value ? (T)value : default(T);
    }