While researching useful features in .NET 9 that could benefit XAF/XPO developers, I discovered something particularly interesting: Version 7 GUIDs (RFC 9562 specification). These new GUIDs offer a crucial feature – they’re sortable.
To demonstrate this improvement, I created a test solution for XAF with a custom base object. The key implementation occurs in the OnSaving method:
protected override void OnSaving()
{
base.OnSaving();
if (!(Session is NestedUnitOfWork) && Session.IsNewObject(this) && oid.Equals(Guid.Empty))
{
oid = Guid.CreateVersion7();
}
}
Notice the use of CreateVersion7() instead of the traditional NewGuid(). For comparison, I also created another domain object using the traditional GUID generation:
protected override void OnSaving()
{
base.OnSaving();
if (!(Session is NestedUnitOfWork) && Session.IsNewObject(this) && oid.Equals(Guid.Empty))
{
oid = Guid.NewGuid();
}
}
When creating multiple instances of the traditional GUID domain object, you’ll notice that the greater the time interval between instance creation, the less likely the GUIDs will maintain sequential ordering.
GUID Version 7
GUID Old Version
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On my GUID, common problems using GUID identifiers | Joche Ojeda