If you want the first element from array, you can use $slice along with $gte. Let us create a collection with documents −
> db.demo640.insertOne({Name:"John","Scores":[80,90,75]}); { "acknowledged" : true, "insertedId" : ObjectId("5e9c2eb86c954c74be91e6e0") } > db.demo640.insertOne({Name:"Chris","Scores":[85,70,89]}); { "acknowledged" : true, "insertedId" : ObjectId("5e9c2ece6c954c74be91e6e1") }
Display all documents from a collection with the help of find() method −
> db.demo640.find();
This will produce the following output −
{ "_id" : ObjectId("5e9c2eb86c954c74be91e6e0"), "Name" : "John", "Scores" : [ 80, 90, 75 ] } { "_id" : ObjectId("5e9c2ece6c954c74be91e6e1"), "Name" : "Chris", "Scores" : [ 85, 70, 89 ] }
Following is the query to projection of arrays using sing $slice −
> db.demo640.find({Scores:{$gte:85}},{ "Scores": {$slice : 1}});
This will produce the following output −
{ "_id" : ObjectId("5e9c2eb86c954c74be91e6e0"), "Name" : "John", "Scores" : [ 80 ] } { "_id" : ObjectId("5e9c2ece6c954c74be91e6e1"), "Name" : "Chris", "Scores" : [ 85 ] }