Mongodb $sample after filtering

Question

Let's say I want a person to find people they're not connected with, I would do:

User.find({ _id: { $nin: req.user.connections })

However, I only want to retrieve at most 10 random documents from the return. In MongoDB, there is $sample:

{ $sample: { size: <positive integer> } }

I've never used Mongo before, so I'm unsure of how to chain these two together in order for me to retrieve 10 random people the current user is unconnected to.

Answer 1

$sample is an aggregation operator, so you need to create an aggregate pipeline that chains the two operations together:

User.aggregate([
    { $match: { _id: { $nin: req.user.connections } } },
    { $sample: { size: 10 } }
])