"Object reference not set to an instance of an object." Error when trying to display AD Results

Question

User678367958 posted

Hello,

i am querying successfully the Active Directory. I am searching for a User and want to show the results. This works fine for the sAMAccountName and the DisplayName, but when i want to show the SN and the GIVENNAME Properties of a User, i get the following Error:

Object reference not set to an instance of an object.

This is my Code:

Dim ds As New DirectorySearcher(searchRoot, String.Format("(&(objectClass=user)(sAMAccountName={0}))", txtSearchString.Text))
                    ds.PropertiesToLoad.Add("sAMAccountName")
                    ds.PropertiesToLoad.Add("DisplayName")
                    ds.PropertiesToLoad.Add("SN")
                    ds.PropertiesToLoad.Add("givenName")
                    ds.SearchScope = SearchScope.Subtree

                    ds.Sort = New SortOption("sAMAccountName", SortDirection.Ascending)
                    Dim sr As SearchResultCollection = ds.FindAll()

                    If sr.Count <> 0 Then
                        For Each i As SearchResult In sr
                            Dim de As DirectoryEntry = i.GetDirectoryEntry

                            response.write(de.Properties("sAMAccountName").Value.ToString)
                            response.write(de.Properties("DisplayName").Value.ToString)
                            response.write(de.Properties("SN").Value.ToString & ", " & de.Properties("givenName").Value.ToString)
                        Next
                    End If

When i use

row("DisplayName") = de.Properties("SN").Value.ToString & ", " & de.Properties("givenName").Value.ToString

i get the Errormessage. But when i comment the above line out and only use:

row("DisplayName") = de.Properties("DisplayName").Value.ToString

everything works fine and it shows me the sAMAccountName and the DisplayName. I have filled the Fields First Name and Last Name for all my Users in the AD!

Answer 1

User1508394307 posted

It can be that sn and givenName are indexed values and can be obtained with index (e.g. de.Properties("sn")(0).ToString()).

Try to use following

If (de.Properties.Contains("sn")) Then
	Response.Write(de.Properties("sn")(0).ToString())
End If

If (de.Properties.Contains("givenName")) Then
	Response.Write(de.Properties("givenName")(0).ToString())
End If

This will check if property exists and return its first value.

Hope this helps.

Answer 2

User678367958 posted

Thanks,

but what are indexed values?

Answer 3

User1508394307 posted

I must say multi-valued attributes. I think usually givenName, and surname are single-valued attributes. So, it's either a problem that they were not populated in DirectorySearcher (this can be checked using Properties.Contains), or these attributes may have multiple values (this can be checked using an index as shown above).

Answer 4

User678367958 posted

The solution was to check if the properties exists (contains), not to use (0) as for multivalue properties.

Answer 5

User-847405884 posted

THANKS A LOT !