Retrieving the next page of items with MSGraph - sharepoint-online

Question

I am trying to get a count of the number of items in a Sharepoint List.
I can obtain counts for lists equal to or less than 200. But each page of results contains 200 items and I cannot figure out how to get the next pages.
int listCount = 0;
Microsoft.Graph.List list = new Microsoft.Graph.List();
var queryOptions = new List<QueryOption>()
{
new QueryOption("select", "id"),
new QueryOption("expand", "columns(select=name),items(expand=fields(select=CustomerName))")
};
GraphServiceClient graphServiceClient = GetAuthenticatedGraphClient(scopes).Result;
list = await graphServiceClient.Sites[$"{siteId}"].Lists[$"{listId}"].Request(queryOptions).GetAsync();
if (list.Items != null)
{
listCount = list.Items.Count;
}
I've read through this
https://learn.microsoft.com/en-us/graph/paging
and this
https://learn.microsoft.com/en-us/graph/sdks/paging?tabs=csharp
However #odata.nextLink isn't in the response, and converting the pageIterator code from messages to lists doesn't return any data at all.
The items object does have a field called NextPageRequest, but it is null.
Does anyone please have some example code on how to obtain more pages of Sharepoint List items after the first page?

Answer 1

I found an answer, with some inspiration from
https://github.com/microsoftgraph/msgraph-sdk-dotnet/issues/891
The answer was to request Lists[{}].Items, which retrieves a ListItemsCollectionPage object which contains a count. If that count is 200, then QueryOptions is used in to repeat the request for the next ItemsPage
int listCount = 0;
Microsoft.Graph.IListItemsCollectionPage listItems;
GraphServiceClient graphServiceClient = GetAuthenticatedGraphClient(scopes).Result;
listItems = await graphServiceClient.Sites[$"{siteId}"].Lists[$"{listId}"].Items.Request().GetAsync();
itemCount = listItems.Count();
var nextPage = listItems.NextPageRequest;
while (nextPage != null)
{
listItems = await graphServiceClient.Sites[$"{siteId}"].Lists[$"{listId}"].Items.Request(nextPage.QueryOptions).GetAsync();
itemCount = itemCount + listItems.Count();
nextPage = listItems.NextPageRequest;
}