Simplifying MongoDB aggregation $project stage-CodePudding

I have the following working $project stage in my MongoDB aggregation pipeline. The issue is that I am not fully happy with it and would like to hear your suggestions on how the stage could be improved:

$project: {
    _id: 0,
    name: 1,
    points: 1,
    level: {
        $cond: {
            if: { $gt: [ "$points", 250 ] },
            then: {
                $cond: {
                    if: { $gt: [ "$points", 500 ] },
                    then: {
                        $cond: {
                            if: { $gt: [ "$points", 3000 ] },
                            then: {
                                $cond: {
                                    if: { $gt: [ "$points", 5000 ] },
                                    then: {
                                        $cond: {
                                            if: { $gt: [ "$points", 20000 ] },
                                            then: 6,
                                            else: 5
                                        }
                                    },
                                    else: 4
                                }
                            },
                            else: 3
                        }
                    },
                    else: 2
                }
            },
            else: 1
        }
    }
}

Basically, what the project stage does is compute a certain level (1-6), based on achieved points. Right now it looks really hard to read and error prone, any suggestions on how to improve would be welcome.

CodePudding user response：

One option is to use $switch:

db.collection.aggregate([
  {$project: {
      _id: 0,
      name: 1,
      points: 1,
      level: {
        $switch: {
          branches: [
            {
              case: {$lte: ["$points", 250]},
              then: 1
            },
            {
              case: {$and: [{$gt: ["$points", 250]}, {$lt: ["$points", 500]}]}, 
              then: 2
            },
            {
              case: {$and: [{$gt: ["$points", 500]}, {$lt: ["$points", 3000]}]}, 
              then: 3
            },
          ],
          default: 4
        }
      }
    }
  }
])

See how it works on the playground example, although it looks like repeating the lower bound is redundent.