Re: Using Generics with System.DirectoryServices
- From: "Willy Denoyette [MVP]" <willy.denoyette@xxxxxxxxxx>
- Date: Tue, 10 Oct 2006 17:04:49 +0200
"Mark Rae" <mark@xxxxxxxxxxxxxxxxx> wrote in message
news:%23%23tVGuF7GHA.4428@xxxxxxxxxxxxxxxxxxxxxxx
| Hi,
|
| I'm in the process of updating an ASP.NET v1.1 web app to v2. The app uses
| ActiveDirectory a great deal, and I'm trying to use the new
| System.Collections.Generic namespace where possible, having been advised
by
| several luminaries that that is a "good thing to do"... :-)
|
| However, I'm experiencing a problem with the IEnumerable interface. (N.B.
I
| understand fully that I should be using the LDAP provider instead of the
| WinNT provider - I'm in the process of fixing that too, but that's not my
| most pressing problem.)
|
| I use the following function to return a list of all users in a group:
|
| using System;
| using System.Collections;
| using System.Collections.Generic;
| using System.DirectoryServices;
|
| public static List<string> GetGroupsForUser(string pstrUser)
| {
| DirectoryEntry objADEntry = null;
| DirectoryEntry objUser = null;
| object objChildren = null;
| List<string> lstGroups = new List<string>();
|
| try
| {
| objADEntry = new DirectoryEntry("WinNT://" + mstrDomain + ",
| domain");
| objUser = objADEntry.Children.Find(pstrUser, "user");
| objChildren = objUser.Invoke("Groups");
| foreach (object objChild in (IEnumerable)objChildren)
| {
| DirectoryEntry objGroup = new DirectoryEntry(objChild);
| lstGroups.Add(objGroup.Name.ToLower());
| }
| return lstGroups;
| }
| catch (Exception)
| {
| throw;
| }
| }
|
|
| It works well enough. However, when I rem out the using
System.Collections;
| namespace reference, the code fails and tells me that there is no support
| for IEnumerable taking no arguments. Fair enough.
|
| If I amend the line in question to:
|
| foreach (object objChild in (IEnumerable<DirectoryEntries>)objChildren)
|
| That returns the following error:
|
| Unable to cast COM object of type 'System.__ComObject' to interface type
|
'System.Collections.Generic.IEnumerable`1[System.DirectoryServices.DirectoryEntries]'.
| This operation failed because the QueryInterface call on the COM component
| for the interface with IID '{AEF9EC8A-1E73-365B-8DA2-800A3A6166E6}' failed
| due to the following
| error: No such interface supported (Exception from HRESULT: 0x80004002
| (E_NOINTERFACE)).
|
|
| At this point, I'm pretty much out of my depth. Therefore, I'd be grateful
| to know:
|
| 1) if what I'm doing is a worthwhile exercise, or whether I should just
| continue with the old IEnumerable object in the old System.Collections
| namespace
|
| 2) apart from replacing WinNT with LDAP, which I'm in the process of
doing,
| is there a more efficient method for returning a list of groups to which a
| user belongs?
|
|
| Any assistance gratefully received.
|
| Mark
|
|
WinNT and LDAP (the providers) implement a diferent object model, so you
can't use the following sample to query group membership in a NT4 domain.
// search all groups myUser is member a of.
// use server or FastBind binding for the fastest way to query the AD.
using(DirectoryEntry user = new DirectoryEntry("LDAP://..., cn=myUser,
cn=.., dn=..", AuthenticationTypes.FastBind))
{
PropertyCollection pcoll = user.Properties;
PropertyValueCollection memberOf = pcoll["memberOf"];
foreach(string group in memberOf)
lstGroups.Add(group);
}
note also that the AD hierarchy differs considerable from NT4's SAM object
model, so the data returned is in the "common name "format (that is :
CN=...) instead of a simple SAM account name.
Willy.
.
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