mongodb_aggregate_query.txt

db.cohorts.aggregate([
    {
        "$match": { "journeyId": "4f1f0071fbe1093a8281" }
    },
    {
        $project: {
            _id: {
                "$toString": "$_id"
            },
            testCohort: 1,
            enabled: 1,
            suppressAnalytics: 1,
            excludeFromDashboard: 1,
            title: 1,
            startDateTime: 1,
            customerId: 1,
            journeyId: 1,
        }
    },
    {
        $lookup: {
            from: "users",
            localField: "_id",
            foreignField: "journeys.cohortId",
            as: "userList"
        }
    },
    {
        $project: {
            _id: 1,
            testCohort: 1,
            enabled: 1,
            suppressAnalytics: 1,
            excludeFromDashboard: 1,
            title: 1,
            startDateTime: 1,
            customerId: 1,
            journeyId: 1,
            userCount: { $size: "$userList" }
        }
    }
])


db.getCollection('cohorts').aggregate([
    { "$match": { "journeyId": "4f1f0071fbe1093a8281" } }
    ,
    {
       $lookup: {
           from: "users",
           let: { cohort_id: "$_id" },
           pipeline: [
              { $match: { "journeys.cohortId": "$$cohort_id" } },
              { $project: { _id: 0, root: { fname: "$fname", lname: "$lname" } } },
              { $replaceRoot: { newRoot: "$root" } }
           ],
           as: "userList"
         }
    }
])