Get Users in Group from Azure AD via Microsoft Gra

I'm requesting a list of users from AzureAD via Microsoft Graph.

I get the User objects back, but their MemberOf property is always null.

I thought I could use Expand to request that property specifically, and while it causes no error it also doesn't populate the property.

This question and answer from mid-2016 suggests this functionality was in beta at that time, and I thought it would have graduated to the production API by now?

var allUsers = await graphClient
    .Users
    .Request()
    .Expand("memberOf")
    .GetAsync();

var usersInGroup = allUsers
    .Where(user => user.MemberOf.Any(memberOf => memberOf.Id.Equals(groupId, StringComparison.OrdinalIgnoreCase)))
    .ToList();

(I've tried expanding "memberOf" and "MemberOf".)

I can retrieve a list of members via the Group.

But that returns a list of IDs, so I'd have to make two requests instead of just the one.

var groupMembers = await graphClient
    .Groups[groupId]
    .Members
    .Request()
    .GetAsync();

var groupMemberIds = groupMembers
    .Select(groupMember => groupMember.Id)
    .ToList();

var allUsers = await graphClient
    .Users
    .Request()
    .GetAsync();

var usersInGroup = allUsers
    .Where(user => groupMemberIds.Contains(user.Id))
    .ToList();

If getting the IDs belonging to the Group, and then filtering the Users is the correct way then that's fine, I'll go with that.

Ideally I'd like to make a single request to retrieve the User objects and have the filtering done server side.

e.g.

var usersInGroup = await graphClient
    .Users
    .Request()
    .Filter($"memberOf eq {groupId}")
    .GetAsync();

Obviously that filter won't work, but something like that would be ideal.

^{_{(It was pointed out that I have been linking to the wrong set of documentation, so I've stripped out those links to prevent confusion for future readers)}}

Getting the membership for a single Group can be done using $expand. For example, running the following query in Graph Explorer will return the Group HRTaskforce and all of it's members:

https://graph.microsoft.com/v1.0/groups/02bd9fd6-8f93-4758-87c3-1fb73740a315?$expand=members

Using the .NET Client SDK, you could do something like this:

var  groupAndMembers = await _tokenService.Token.GetGraphServiceClient()
    .Groups["02bd9fd6-8f93-4758-87c3-1fb73740a315"]
    .Request()
    .Expand("members")
    .GetAsync();

var usersInGroup = groupAndMembers.Members.ToList();

One aside, all of the documentation you linked to is from the Azure AD Graph API. Please note that this is a different API and it is not always safe to assume that resources and methods from Azure AD Graph will be available (or work the same way) as Microsoft Graph