Duplicate LINQ to SQL entity / record?

Question

What would be considered the best practice in duplicating [cloning] a LINQ to SQL entity resulting in a new record in the database?

The context is that I wish to mak

Answer 1

Create a new instance and then use the linq mapping classes together with reflection to copy member values.

E.g.

public static void CopyDataMembers(this DataContext dc,
                                   object sourceEntity,
                                   object targetEntity)
{
    //get entity members
    IEnumerable dataMembers = 
         from mem in dc.Mapping.GetTable(sourceEntity.GetType())
                                 .RowType.DataMembers
         where mem.IsAssociation == false
         select mem;

    //go through the list of members and compare values
    foreach (MetaDataMember mem in dataMembers)
    {
       object originalValue = mem.StorageAccessor.GetBoxedValue(targetEntity);
       object newValue = mem.StorageAccessor.GetBoxedValue(sourceEntity);

        //check if the value has changed
        if (newValue == null && originalValue != null 
            || newValue != null && !newValue.Equals(originalValue))
        {
            //use reflection to update the target
            System.Reflection.PropertyInfo propInfo = 
                targetEntity.GetType().GetProperty(mem.Name);

            propInfo.SetValue(targetEntity, 
                              propInfo.GetValue(sourceEntity, null), 
                              null);

            // setboxedvalue bypasses change tracking - otherwise 
            // mem.StorageAccessor.SetBoxedValue(ref targetEntity, newValue);
            // could be used instead of reflection
        }
    }
}

...or you can clone it using the DataContractSerializer:

internal static T CloneEntity(T originalEntity) where T : someentitybaseclass
{
    Type entityType = typeof(T);

    DataContractSerializer ser =
        new DataContractSerializer(entityType);

    using (MemoryStream ms = new MemoryStream())
    {
        ser.WriteObject(ms, originalEntity);
        ms.Position = 0;
        return (T)ser.ReadObject(ms);
    }
}