SharePoint People.asmx web service returns -1 - web-services

Question

When I query my web service to find a user, if that user is not part of a SharePoint group for the site, the ID is -1.
However, the user CAN get to the site, via a group permission. So my web service call cannot add the user to a "people" box within a list, even though SharePoint itself CAN add it.
My Web service call is as follows:
String searchText = "[My User's Login Name, Spelled Exactly as it appears in SharePoint.]";
String maxresults = "100";
String pType = "All";
String body = "<?xml version=\"1.0\"?>"
+ "<soap:Envelope xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\" "
+ " xmlns:xsd=\"http://www.w3.org/2001/XMLSchema\" "
+ " xmlns:soap=\"http://schemas.xmlsoap.org/soap/envelope/\">"
+ "<soap:Body>"
+ " <SearchPrincipals "
+ " xmlns=\"http://schemas.microsoft.com/sharepoint/soap/\">"
+ " <searchText>" + searchText + "</searchText>"
+ " <maxResults>" + maxResults + "</maxResults>"
+ " <principalType>" + pType + "</principalType>"
+ " </SearchPrincipals>"
+ " </soap:Body>"
+ "</soap:Envelope>";
I get the following response from the web service call:
<?xml version="1.0" encoding="utf-8"?>
<soap:Envelope
xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:xsd="http://www.w3.org/2001/XMLSchema">
<soap:Body>
<SearchPrincipalsResponse xmlns="http://schemas.microsoft.com/sharepoint/soap/">
<SearchPrincipalsResult>
<PrincipalInfo>
<AccountName>[User's Account Name]</AccountName>
<UserInfoID>-1</UserInfoID> <------------ NOTE THE -1 HERE -----------------
<DisplayName>[User's full name, exactly as I sent it in]</DisplayName>
<Email>...</Email>
<Department>...</Department>
<Title>...</Title>
<IsResolved>true</IsResolved>
<PrincipalType>User</PrincipalType>
</PrincipalInfo>
</SearchPrincipalsResult>
</SearchPrincipalsResponse>
</soap:Body>
</soap:Envelope>
If I use this information to add a user to a "people" box, via the web service, The entry becomes "-1;#My User Name", which of course it cannot find, so the List.asmx webservice returns an error of 0x81020054 : The user does not exist or is not unique.
When I add the user to a group within the site directly, their ID resolves out just fine and everything goes through as normal. I remove them from the group and it returns to -1 again.
Any thoughts and/or suggestions for always returning a valid ID?

Answer 1

I can see you are using SearchPrincipals method. Instead try using ResolvePrincipals method.
Documentation here: http://msdn.microsoft.com/en-us/library/people.people.resolveprincipals(v=office.12).aspx
That method has a bool parameter where you can specify that if the user does not belong to the site, then it should be added, this way you will always make sure that you are always getting the ID even if the user does not belong to the site.
PeopleWebService.People pe = new PeopleWebService.People(); //People.asmx web service
string[] users = new string[] { "youruser" };
PeopleWebService.PrincipalInfo[] pInfo = pe.ResolvePrincipals(users, PeopleWebService.SPPrincipalType.User, true); //third param is true
string userID = pInfo[0].UserInfoID.ToString();