Template
single collection
multiple collections
mgodatagen
update
indexe
explain
Stage
Database
bson
mgodatagen
[{_id:1,persons:[{name:"Jack",age:12},{name:"Ma",age:13}]}]
Query
db.collection.find({},{"person":{$reduce:{input:"$persons",initialValue:{},in:{$cond:[{$eq:["$$this.name","Jack"]},"$$this","$$value"]}}}})
Result