I have the following docs in my collection -

{
  name: 'test1',
  score: 80
},
{
  name: 'test2',
  score: 50
},
{
  name: 'test3',
  score: 100
},
{
  name: 'test4',
  score: 70
}

I would like to aggregate and group those docs, based on scores ranges - 0-60, 61-90, 91-100

so the results will look like -

{
  score: '0-60',
  tests: ['test2']
}, 
{
  score: '61-90',
  tests: ['test1', 'test4']
}, 
{
  score: '91-100',
  tests: ['test3']
}

Can I somehow group values by ranges in MongoDB?

CodePudding user response：

db.collection.aggregate([
  {
    $addFields: {
      range: {//Create customised ranges
        $switch: {
          branches: [
            {
              case: {
                $lte: [
                  "$score",
                  60
                ]
              },
              then: "0-60"
            },
            {
              case: {
                $lte: [
                  "$score",
                  90
                ]
              },
              then: "61-90"
            },
            {
              case: {
                $lte: [
                  "$score",
                  100
                ]
              },
              then: "91-100"
            }
          ],
          default: "invalid"
        }
      }
    }
  },
  {
    "$group": {//Group on the range
      "_id": "$range",
      "tests": {
        "$push": "$name"
      }
    }
  }
])

playground

CodePudding user response：

You may check also the $bucketAuto aggregation operator which allow you to auto group by range based on number of ranges:

db.collection.aggregate([
  {
    $bucketAuto: {
     groupBy: "$score",
     buckets: 3
    }
  }
])

Explained: You provide the field in groupBy by which you need to group and you provide the number of ranges.

Playground