I have an addressmodel like this:

const AddressSchema = new Schema({
    address: String,
    city: String,
    postal_code: String,
    country: String,
    user_id: String,
    postalCodeMeters: Number,
});

And I want to know (for a certain user at a certain postal_code):

• How many unique addresses have been visited
• How many times have the user visited this postal code
• How many meters have they traveled

This code works, but I want to do it in one query, not two:

addressrouter.get("/isexplored/:userid/:postalcode",
    async (req, res) => {
      console.log(req.params.userid)
      try {
        const addresses = await Address.aggregate(
          [
            { $match:{
              user_id: req.params.userid,
              postal_code: req.params.postalcode
            }},
            {$group: {
              _id: null,
              meters: {$sum: "$postalCodeMeters"},
              count: { $sum: 1 }
            }
          }]
        )
        console.log(addresses)
        const uniqueAddresses = (await Address.find(
          {
            user_id: req.params.userid,
            postal_code: req.params.postalcode
          }
        ).distinct('address')).length
        res.json({
          time: addresses[0].count,
          uniqueAddressesVisited: uniqueAddresses,
          meters: addresses[0].meters
        });
      } catch (err) {
        console.log(err)
        res.json({ message: err });
      }
    }
  )

CodePudding user response：

If I've understood correctly you can do it in a single $group operation.

Check this query where using $addToSet in the $group stage we can get the unique values. And after that use $size into project to know the length.

Address.aggregate([
  {
    "$match": {
      "user_id": req.params.userid,
      "postal_code": req.params.postalcode
    }
  },
  {
    "$group": {
      "_id": null,
      "meters": {
        "$sum": "$postalCodeMeters"
      },
      "count": {
        "$sum": 1
      },
      "address": {
        "$addToSet": "$address"
      }
    }
  },
  {
    "$project": {
      "_id": 0,
      "count": 1,
      "meters": 1,
      "uniqueAddressesVisited": {
        "$size": "$address"
      }
    }
  }
])

Example here