Uppercase and lowercase mapping of GUID in Glass.Mapper

Question

what determines on how GUID are mapped from sitecore using Glass.Mapper: uppercase vs lowercase?

Now I see it's lowercase but I can bet I had in the past uppercase.

Answer 1

System.Guid is lowercase and Sitecore.Data.ID is uppercase. The two are interchangeable. new ID(Guid id) vs sitecoreId.Guid. This can be particularly important when working with indexes, as Sitecore ID's are typically stored as lowercase without braces and hyphens in the index. So in n index queries, you can use mySitecoreID.Guid.ToString('N')