28.5 Searching with DirectorySearcher

We've shown how easy it is to read individual objects from Active Directory with the DirectoryEntry class, so let's now look at how to search Active Directory with the DirectorySearcher class. The DirectorySearcher class works like many other LDAP-based search APIs. Table 28-4 contains all of the DirectorySearcher properties.

Many of the properties, such as SearchScope, should look familiar. The following code shows how to search for all user objects in the mycorp.com domain.

Dim objSearch As New DirectorySearcher(  )
objSearch.SearchRoot = New DirectoryEntry("LDAP://dc=mycorp,dc=com")
objSearch.Filter = "(&(objectclass=user)(objectcategory=person))"
objSearch.SearchScope = SearchScope.Subtree
objSearch.PropertiesToLoad.Add("cn")
Dim colQueryResults As SearchResultCollection
colQueryResults = objSearch.FindAll(  )
Dim objResult As SearchResult
For Each objResult In colQueryResults
    Console.WriteLine(objResult.Properties("cn")(0))
Next

After a new DirectorySearcher class was instantiated, we set four properties before executing the search. The SearchRoot accepts a DirectoryEntry object representing the search base; the Filter property is the LDAP filter string; SearchScope is one of the values contained in the System.DirectoryServices.SearchScope enumeration; and PropertiesToLoad.Add( ) builds the attribute list to return from the query. You can specify multiple attributes in a single statement by using PropertiesToLoad.AddRange:

objSearch.PropertiesToLoad.AddRange(New String(  ) {"cn", "sn", "givenname"})

After all of the search parameters have been set, we can use the FindAll( ) method to invoke the search. A System.DirectoryServices.SearchResultsCollection is returned by the FindAll( ) method, and you can iterate over each entry using a For Each loop. The SearchResultsCollection contains System.DirectoryServices.SearchResult objects, which are very similar to DirectoryEntry objects.

If you want to retrieve only the first object in the search results, you can use the FindOne( ) method, which returns a single SearchResult object.