I am using SP web services (usergroup.asmx.GetUserCollectionFromSite()) to get the user IDs of users that I am programmatically adding to a usermulti field in a list.

Apparently this is not the user ID that is used in the User field as it ends up mapping to a different user.


My ID from GetUserCollectionFromSite() is 26. If I programmatically look at a list with my username in it, it is: 9;#My.UserName

Where does the ID part of the User Field come from?

1 Answer 1


SPFieldUserValue is inherited from SPFieldLookupValue. So there is a lookup list. It is hidden user information list. You can get it from SPWeb.SiteUserInfoList or from /_catalogs/users/simple.aspx

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