GraphServiceClient PageItarator failes with 'The Parsable does not contain a collection property'

Question

I wanted to use the PageIterator in my project, and it works perfectly until I wanted to take out group members from AzureAD. No matter what I do, the PageIterator failes with 'The Parsable does not contain a collection property'.

List<User> users = new();
var result = await graphClient.Groups[groupId].Members.GetAsync((requestConfiguration) =>
    {
       requestConfiguration.QueryParameters.Top = 2;
       // I only do this to force pageing, will not be on final version
    });

var pageIterator = PageIterator<User, DirectoryObjectCollectionResponse>
    .CreatePageIterator(graphClient, result,
         (m) =>
         {
             users.Add(m);
             return true;
         });

await pageIterator.IterateAsync();

My code forces 2 items. It's only because I, in a desperate attempt, tries to figure out what is wrong with my code.

I am left clueless on what's wrong here and any help would be awesome.

Answer 1

I reproduced your issue in my side and I changed the code like below:

var pageIterator = PageIterator<DirectoryObject, DirectoryObjectCollectionResponse>
                .CreatePageIterator(graphClient, result,
                     (m) =>
                     {
                         if (m.OdataType == "#microsoft.graph.group")
                         {
                             return true;
                         }
                         else if (m.OdataType == "#microsoft.graph.user")
                         {
                             users.Add((User)m);
                             return true;
                         }
                         else {
                             return true;
                         }
                     });

The issue happened at the response type. List Member API will return directoryObject as the response, but in your code, you had PageIterator<User, DirectoryObjectCollectionResponse> which causing the error.

By the way, if we only want to get user members, then we may change code like this:

var result = await graphClient.Groups["group_id"].Members.GraphUser.GetAsync((requestConfiguration) =>
            {
                requestConfiguration.QueryParameters.Top = 1;
            });
            var pageIterator = PageIterator < User, UserCollectionResponse>
                .CreatePageIterator(graphClient, result,
                     (m) =>
                     {
                        users.Add(m);
                        return true;
                     });