Graph API: What is the correct way to interrupt Pagination

Question

I am using this script to fetch Chats. I need 100 chats maximum but it may happen that a chat do not have 100 messages. How can I handle that case in this script?

I am using Node Package Microsoft Graph Client.

    const { Client, PageIterator } = require('@microsoft/microsoft-graph-client');
    async getChatList(GroupChatId) {
        let messages = [];

        let count = 0;
        let pauseAfter = 100; // 100 messages limit

        let response = await this.graphClient
            .api(`/chats/${GroupChatId}/messages`)
            .version('beta')
            .get();


        let callback = (data) => {
            messages.push(data);
            count++;
            return count < pauseAfter;
        }

        let pageIterator = new PageIterator(this.graphClient, response, callback);
        await pageIterator.iterate();

        return messages;

    }

Answer 1

As I answered on the GitHub issue you opened, the iterator should stop all by itself if it runs out of items to iterate before hitting your "maximum". However, I think you're hitting a bug in the specific API you're using /chats/id/messages.

The problem is that this API is returning a nextLink value in it's response even if there are no next pages. It shouldn't be, and I'm reporting that to the Teams folks. That's causing the pageIterator to try to get the next set of results, which returns 0 items and a nextLink. You're stuck in an infinite loop.

So because of this, using the pageIterator just won't work for this API. You'll need to do the iteration yourself. Here's some TypeScript code to show it:

let keepGoing: Boolean = true;
do
{
  // If there are no items in the page, then stop
  // iterating.
  keepGoing = currentPage.value.length > 0;

  // Loop through the current page
  currentPage.value.forEach((message) => {
    console.log(JSON.stringify(message.id));
  });

  // If there's a next link follow it
  if (keepGoing && !isNullOrUndefined(currentPage["@odata.nextLink"]))
  {
    currentPage = await client
      .api(currentPage["@odata.nextLink"])
      .get();
  }
} while (keepGoing);