Sorting and ranking matching elements in a nested array list in MongoDB

user_2334114 0
Viewed 101

Greetings fellow fans of MongoDB!

I've got here a data structure with board game data where achieved scores (after every round) are tracked as nested arrays associated with the player's name. Note that with each board game there's a different set of players:

{
"BoardGames" : {
    "Game1" : {
        "players" : {
            "Anne" : [97, 165, 101, 67],
            "Pete" : [86, 115, 134, 149],
            "Scott" : [66, 89, 103, 74],
            "Jane" : [113, 144, 125, 99],
            "Katie" : [127, 108, 98, 151]
        }
    },
    "Game2" : {
        "players" : {
            "Margot" : [1, 0, 0, 0],
            "Pete" : [0, 0, 1, 1],
            "Michael" : [0, 0, 0, 0],
            "Jane" : [0, 0, 1, 0]
        }
    },
    "Game3" : {
        "players" : {
            "Chris" : [6, 2, 4, 0, 5, 7],
            "Pete" : [4, 5, 2, 5, 3, 1, 4],
            "Julia" : [3, 7, 4, 0],
            "Tom" : [3, 2, 4, 8, 2, 6, 7]
        }
    },
}
  • Game1: Players earn as many victory points per round as they can
  • Game2: Winning around earns 1, losing a round 0
  • Game3: Players may leave after every round, hence some players have played more rounds than others, so these arrays are different in their length

So, here are my questions:

  1. Which player got the most points in each game? Who the least?
  2. Who is the winner in the first round? 2nd round, etc.
  3. Who is sitting on 1st, 2nd and 3rd rank from all played games?

I've done quite some queries with mongo, but so far with a nested array that is attached to a flexible/unpredictable parent node I have no idea how to write a query. Also, maybe this is not the best way how I structured the data. So in case you have a better idea, I'd be happy to learn!

Cheers!

P.S.: The insertMany statement to above JSON data:

db.boardGames.insertMany([
{
    "_id" : 1,
    "Game1" : {
        "players" : {
            "Anne" : [97, 165, 101, 67],
            "Pete" : [86, 115, 134, 149],
            "Scott" : [66, 89, 103, 74],
            "Jane" : [113, 144, 125, 99],
            "Katie" : [127, 108, 98, 151]
        }
    },
    "Game2" : {
        "players" : {
            "Margot" : [1, 0, 0, 0],
            "Pete" : [0, 0, 1, 1],
            "Michael" : [0, 0, 0, 0],
            "Jane" : [0, 0, 1, 0]
        }
    },
    "Game3" : {
        "players" : {
            "Chris" : [6, 2, 4, 0, 5, 7],
            "Pete" : [4, 5, 2, 5, 3, 1, 4],
            "Julia" : [3, 7, 4, 0],
            "Tom" : [3, 2, 4, 8, 2, 6, 7]
        }
    }
}]);
mongodb-query mongodb arrays
1 Answers

the schema you have is not ideal. if it was something like this: https://mongoplayground.net/p/o8m205t9UKG then you can query like the following:

find winner of each game:

db.collection.aggregate(
[
    {
        $set: {
            Players: {
                $map: {
                    input: "$Players",
                    as: "x",
                    in: {
                        Name: "$$x.Name",
                        TotalScore: { $sum: "$$x.Scores" }
                    }
                }
            }
        }
    },
    {
        $unwind: "$Players"
    },
    {
        $sort: { "Players.TotalScore": -1 }
    },
    {
        $group: {
            _id: "$Name",
            Winner: { $first: "$Players.Name" }
        }
    }
])

find top 3 ranking players across all games:

db.collection.aggregate(
[
    {
        $set: {
            Players: {
                $map: {
                    input: "$Players",
                    as: "x",
                    in: {
                        Name: "$$x.Name",
                        TotalScore: { $sum: "$$x.Scores" }
                    }
                }
            }
        }
    },
    {
        $unwind: "$Players"
    },
    {
        $group: {
            _id: "$Players.Name",
            TotalScore: { $sum: "$Players.TotalScore" }
        }
    },
    {
        $sort: { TotalScore: -1 }
    },
    {
        $limit: 3
    },
    {
        $group: {
            _id: null,
            TopRanks: { $push: "$_id" }
        }
    },
    {
        $project: {
            _id: 0,
            TopRanks: 1
        }
    }
])

find the winner of each round across all games

db.collection.aggregate(
[
    {
        $set: {
            "Players": {
                $map: {
                    input: "$Players",
                    as: "p",
                    in: {
                        Scores: {
                            $map: {
                                input: "$$p.Scores",
                                as: "s",
                                in: {
                                    Player: "$$p.Name",
                                    Round: { $add: [{ $indexOfArray: ["$$p.Scores", "$$s"] }, 1] },
                                    Score: "$$s"
                                }
                            }
                        }
                    }
                }
            }
        }
    },
    {
        $unwind: "$Players"
    },
    {
        $unwind: "$Players.Scores"
    },
    {
        $replaceRoot: { newRoot: "$Players.Scores" }
    },
    {
        $sort: {
            Round: 1,
            Score: -1
        }
    },
    {
        $group: {
            _id: "$Round",
            Winner: { $first: "$Player" }
        }
    },
    {
        $project: {
            _id: 0,
            Round: "$_id",
            Winner: 1
        }
    },
    {
        $sort: {
            Round: 1
        }
    }
])
user_43684850
Related