Ich habe folgende Daten:
{ "_id" : ObjectId("5b82958518aae6c2d2cd429e"), "troops" : [ { "name" : "Baby Dragon", "village" : "builderBase" }, { "name" : "Beta Minion", "village" : "builderBase" }, { "name" : "Bomber", "village" : "builderBase" }, { "name" : "Boxer Giant", "village" : "builderBase" }, { "name" : "Cannon Cart", "village" : "builderBase" }, { "name" : "Night Witch", "village" : "builderBase" }, { "name" : "Raged Barbarian", "village" : "builderBase" }, { "name" : "Sneaky Archer", "village" : "builderBase" }, { "name" : "Archer", "village" : "home" }, { "name" : "Baby Dragon", "village" : "home" }, { "name" : "Balloon", "village" : "home" }, { "name" : "Barbarian", "village" : "home" }, { "name" : "Bowler", "village" : "home" }, { "name" : "Dragon", "village" : "home" }, { "name" : "Giant", "village" : "home" }, { "name" : "Goblin", "village" : "home" }, { "name" : "Golem", "village" : "home" }, { "name" : "Healer", "village" : "home" }, { "name" : "Hog Rider", "village" : "home" }, { "name" : "Lava Hound", "village" : "home" }, { "name" : "Miner", "village" : "home" }, { "name" : "Minion", "village" : "home" }, { "name" : "P.E.K.K.A", "village" : "home" }, { "name" : "Valkyrie", "village" : "home" }, { "name" : "Wall Breaker", "village" : "home" }, { "name" : "Witch", "village" : "home" }, { "name" : "Wizard", "village" : "home" } ] }
{ "_id" : ObjectId("5b82958518aae6c2d2cd42a1"), "troops" : [ { "name" : "Baby Dragon", "village" : "builderBase" }, { "name" : "Beta Minion", "village" : "builderBase" }, { "name" : "Bomber", "village" : "builderBase" }, { "name" : "Boxer Giant", "village" : "builderBase" }, { "name" : "Cannon Cart", "village" : "builderBase" }, { "name" : "Raged Barbarian", "village" : "builderBase" }, { "name" : "Sneaky Archer", "village" : "builderBase" }, { "name" : "Archer", "village" : "home" }, { "name" : "Baby Dragon", "village" : "home" }, { "name" : "Balloon", "village" : "home" }, { "name" : "Barbarian", "village" : "home" }, { "name" : "Bowler", "village" : "home" }, { "name" : "Dragon", "village" : "home" }, { "name" : "Electro Dragon", "village" : "home" }, { "name" : "Giant", "village" : "home" }, { "name" : "Goblin", "village" : "home" }, { "name" : "Golem", "village" : "home" }, { "name" : "Healer", "village" : "home" }, { "name" : "Hog Rider", "village" : "home" }, { "name" : "Ice Golem", "village" : "home" }, { "name" : "Lava Hound", "village" : "home" }, { "name" : "Miner", "village" : "home" }, { "name" : "Minion", "village" : "home" }, { "name" : "P.E.K.K.A", "village" : "home" }, { "name" : "Valkyrie", "village" : "home" }, { "name" : "Wall Breaker", "village" : "home" }, { "name" : "Witch", "village" : "home" }, { "name" : "Wizard", "village" : "home" } ] }
und ich versuche, die unterschiedlichen Werte aus dem zu erhalten home troops.village. Das Basic (ungefiltert) distinctgibt die erwarteten Ergebnisse zurück (alle Werte troopsunabhängig von troops.village):
> db.players.distinct("troops.name")
["Archer", "Baby Dragon", "Balloon", "Barbarian", "Beta Minion", "Bomber", "Bowler", "Boxer Giant", "Cannon Cart", "Dragon", "Giant", "Goblin", "Golem", "Healer", "Hog Rider", "Lava Hound", "Miner", "Minion", "Night Witch", "P.E.K.K.A", "Raged Barbarian", "Sneaky Archer", "Valkyrie", "Wall Breaker", "Witch", "Wizard", "Electro Dragon", "Ice Golem", "Battle Blimp", "Drop Ship", "Hog Glider", "Stone Slammer", "Super P.E.K.K.A", "Wall Wrecker", "Yeti", "Siege Barracks"]
Ich habe folgendes versucht:
> db.players.distinct("troops.name", {"village": "home"})
// This returns an empty set
Ich habe es auch versucht:
> db.players.distinct("troops.name", {"troops.village": "home"})
// This returns the exact same result set as distinct unfiltered, above.
Der "query"Teil von different ist auf Dokumentebene anwendbar, während Sie versuchen, ihn für Unterdokumente zu verwenden, sodass er in diesem Fall nicht funktioniert. Sie müssen $ filter und $ setUnion verwenden , um eindeutige, gefilterte Werte innerhalb eines einzelnen Dokuments zu erhalten:
db.collection.aggregate([
{
$project: {
distinctHomeNames: { $setUnion: { $filter: { input: "$troops", cond: { $eq: [ "$$this.village", "home" ] } } } }
}
}
])
BEARBEITEN: Version mit $ map , um Namen nur hier zu drucken
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