My approach to saving created / updated timestamps and user ID with Entity Framework Core in .NET

DbContext.cs

    private void DatabaseContext_SavingChanges(object? sender, SavingChangesEventArgs e)
    {
        if (sender is not DatabaseContext dbContext)
        {
            return;
        }

        AddTimeStamps(dbContext.ChangeTracker, DateTime.UtcNow);
    }

    private void AddTimeStamps(ChangeTracker changeTracker, DateTime dateTime)
    {
        foreach (var entityEntry in changeTracker.Entries())
        {
            if (entityEntry.Entity is not BaseEntity baseEntity)
            {
                continue;
            }

            switch (entityEntry.State)
            {
                case EntityState.Added:
                    baseEntity.DateCreated = dateTime;
                    if (_tenantId is not null)
                    {
                        baseEntity.CreatedByUserId = _tenantId;
                    }
                    break;

                case EntityState.Modified:
                    baseEntity.DateCreated ??= baseEntity.DateUpdated = dateTime;
                    if (_tenantId is not null)
                    {
                        baseEntity.CreatedByUserId ??= baseEntity.UpdatedByUserId = _tenantId;
                    }
                    break;
            }
        }
    }