mongodb multiple aggregates in same query, each with total

Question

Trying to do aggregate group with more than one { $sum: '$total' }

db.transactions.aggregate([{$group: {_id: '$cashier', cost: {$sum: "$total"}}}, {$group:
{_id: '$deviceid', cost: {$sum: "$total"}}}  ])

When i use two aggregates, the second aggregate returns 0. Av tried to use $project but still i loose get zero.

Answer 1

You need to use $facet

db.transactions.aggregate([
  {
    $facet: {
      cashier: [
        {
          $group: {
            _id: "$cashier",
            cost: {
              $sum: "$total"
            }
          }
        }
      ],
      deviceId: [
        {
          $group: {
            _id: "$deviceid",
            cost: {
              $sum: "$total"
            }
          }
        }
      ]
    }
  }
])

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