Ticket: Get Comments

MongoDB University M220JS: MongoDB for Javascript Developers
#1

Here is my implementation. It failed. What is wrong here?

const pipeline = [
        {
            $match: {
            _id: ObjectId(id)
          },
        },
        {
          $lookup: {
            from: "comments",
            let: {id: "$_id"},
            pipeline: [
            {
              $match:{
                $expr: {
                  $eq: ["movie_id", "$$id"],
                },
              },
            },
            {
              $sort: { date: -1 },
            },
          ],
          as: "comments"
        },
      },
    ]
#2

More details about how it fails would be very useful.

#3

I found it. Missing $ in “$movie_id”. Thank you.

#4