MongoDB সংগ্রহ থেকে সমস্ত নেস্টেড ক্ষেত্রগুলি কীভাবে পুনরুদ্ধার করবেন?

এর জন্য, aggregate() ব্যবহার করুন। আসুন নথি-

>db.demo138.insertOne({"Id":101,"PlayerDetails":[{"PlayerName":"Chris","PlayerScore":400},{"PlayerName":"David","PlayerScore":1000}]});
{
   "acknowledged" : true,
   "insertedId" : ObjectId("5e31bb9ffdf09dd6d08539a1")
}
>db.demo138.insertOne({"Id":102,"PlayerDetails":[{"PlayerName":"Bob","PlayerScore":500},{"PlayerName":"Carol","PlayerScore":600}]});
{
   "acknowledged" : true,
   "insertedId" : ObjectId("5e31bbcefdf09dd6d08539a2")
}

Find() পদ্ধতি -

> db.demo138.find();

এটি নিম্নলিখিত আউটপুট −

{
   "_id" : ObjectId("5e31bb9ffdf09dd6d08539a1"), "Id" : 101, "PlayerDetails" : [
      { "PlayerName" : "Chris", "PlayerScore" : 400 },
      { "PlayerName" : "David", "PlayerScore" : 1000 }
   ]
}
{
   "_id" : ObjectId("5e31bbcefdf09dd6d08539a2"), "Id" : 102, "PlayerDetails" : [
      { "PlayerName" : "Bob", "PlayerScore" : 500 }, { "PlayerName" : "Carol", "PlayerScore" : 600 }
   ] 
}

সংগ্রহ −

> db.demo138.aggregate([{ $unwind:"$PlayerDetails" }, { $project: { "PlayerName":"$PlayerDetails.PlayerName", "PlayerScore":"$PlayerDetails.PlayerScore" } } ] );

এটি নিম্নলিখিত আউটপুট −

{ "_id" : ObjectId("5e31bb9ffdf09dd6d08539a1"), "PlayerName" : "Chris", "PlayerScore" : 400 }
{ "_id" : ObjectId("5e31bb9ffdf09dd6d08539a1"), "PlayerName" : "David", "PlayerScore" : 1000 }
{ "_id" : ObjectId("5e31bbcefdf09dd6d08539a2"), "PlayerName" : "Bob", "PlayerScore" : 500 }
{ "_id" : ObjectId("5e31bbcefdf09dd6d08539a2"), "PlayerName" : "Carol", "PlayerScore" : 600 }