My mongoose schema has the following interface:

interface Voucher {
  ...
  dateRedeemed?: Date;
  merchant: string; // username of merchant
  paymentStatus: 'paid' | 'unpaid';
  ...
}

By executing VoucherModel.aggregate I want to return the result that has the following interface for a given merchant:

{
  totalPaid: number,   //total count of where paymentStatus === 'paid'
  totalUnpaid: number, //total count of where paymentStatus === 'unpaid'
  totalRedeemed: Date, //total count of where dateRedeemed is defined
  totalUnredeemed: Date, //total count of where dateRedeemed is undefined
}

CodePudding user response：

One option is to use $group for this:

db.collection.aggregate([
  {$match: {merchant: merchant, currency: currency}},
  {$group: {
      _id: 0,
      totalPaid: {$sum: {$cond: [{$eq: ["$paymentStatus", "paid"]}, 1, 0]}},
      totalUnredeemed: {$sum: {$ifNull: ["$dateRedeemed", 1, 0]}},
      total: {$sum: 1}
  }},
  {$project: {
      totalPaid: 1,
      totalUnpaid: {$subtract: ["$total", "$totalPaid"]},
      totalRedeemed: {$subtract: ["$total", "$totalUnredeemed"]},
      totalUnredeemed: 1
  }}
])

See how it works on the playground example