MongoDB group by ranges on multiple fields

Question

I have the following docs in my DB:

{
  Age : 10,
  BPM : 20,
  Price: 6
},
{
  Age : 12,
  BPM : 30,
  Price: 9
},
{
  Age : 15,
  BPM : 40,
  Price: 6
},
{
  Age : 10,
  BPM : 46,
  Price: 7
},
{
  Age : 20,
  BPM : 60,
  Price: 8
}

I need help to write an aggregate query to find out for groups (age range 10-15 & BPM 20-50), (age range 15 - 20 & BPM 40 - 90), What is the total sum of prices for each group of ranges. There can be few more groups of ranges.

Answer 1

When you have multiple conditions, one option is to use $switch:

db.collection.aggregate([
  {$set: {
      group: {$switch: {
          branches: [
            {case: {
                $and: [
                  {$gte: ["$Age", 10]},
                  {$lt: ["$Age", 15]},
                  {$gte: ["$BPM", 20]},
                  {$lt: ["$BPM", 50]}
                ]
            }, then: 1},
            {case: {
                $and: [
                  {$gte: ["$Age", 15]},
                  {$lt: ["$Age", 20]},
                  {$gte: ["$BPM", 40]},
                  {$lt: ["$BPM", 90]}
                ]
            }, then: 2}
          ],
          default: "Did not match"
      }}
  }},
  {$group: {_id: "$group", totalSumOfPrices: {$sum: "$Price"}}}
])

See how it works on the playground example