mongodb get filtered count - mongodb

Question

I have no extended knowledge on how to create mongodb queries, but I wanted to ask how could I query collection get something like this:
{
Total: 1000,
Filtered: 459,
DocumentArray: []
}
Of course doing that in one query, so I do not need to do something like this:
db.collection.find();
db.collection.find().count();
db.colection.count();

Answer 1

Well you could do something along these lines:
Considering documents like this:
{ "_id" : ObjectId("531251829df82824bdb53578"), "name" : "a", "type" : "b" }
{ "_id" : ObjectId("531251899df82824bdb53579"), "name" : "a", "type" : "c" }
{ "_id" : ObjectId("5312518e9df82824bdb5357a"), "type" : "c", "name" : "b" }
And an aggregate pipeline like this:
db.collection.aggregate([
{ "$group": {
"_id": null,
"totalCount": { "$sum": 1 },
"docs": { "$push": {
"name": "$name",
"type": "$type"
}},
}},
{ "$unwind": "$docs" },
{ "$match": { "docs.name": "a" } },
{ "$group": {
"_id": null,
"totalCount": { "$first": "$totalCount" },
"filteredCount": { "$sum": 1 },
"docs": { "$push": "$docs" }
}}
])
But I would not recommend it. It will certainly blow up on any "real" collection due to exceeding the maximum BSON document size. And I would doubt it would be performing very well. But that is how it can be done, even if the utility is purely academic.
Just do what you are doing if you need the information. That is the "right way" to do it.