Mongo query with date condition and join of second collection - mongodb

Question

So I have my "user" and "userprofile: collection and I need to find a way to get all users which do satisfy my criteria.
First condition is:
db.userprofile.find( { "country":{$ne:""}, "state":{$ne:""} }
).count()
From my user condition I however need to get all users with certain registration date like this:
db.user.find( {created_at: { $gte:
ISODate("2016-04-25T00:00:00.000Z"), $lt:
ISODate("2016-10-27T00:00:00.000Z") }, } ).count()
userprofile collection contains field "user_id" which is basically the same value like "id" auto generated field from user collection.
SO question is how can I join all users who match date criteria with all users who match userprofile criteria ?
I tried with sample similar to this one but without success:
db.user.aggregate([ {
$lookup:
{
from: "userprofile",
localField: "_id",
foreignField: "userid",
as: "user_profile"
} }, {
$unwind:"$user_profile" }, {
$match: { "user_profile":
{
"country":{$ne:""},
"state":{$ne:""} } } } ]).count()
Update:
db.user.findOne()
{
"_id" : ObjectId("561fac55c9368676ac000001"),
"username" : "somexxx3",
"firstname" : "Some",
"lastname" : "User",
"created_at" : ISODate("2015-10-15T13:38:29.954Z"),
"enabled" : false
}
db.userprofile.findOne()
db.userprofiles.findOne()
{
"_id" : ObjectId("56ec222017be1b7c763898a4"),
"user_id" : ObjectId("56a77f6c17be1b0a4393d8ea"),
"email" : "someuser#gmail.com",
"country" : "United Sates",
"state" : "New York"
}
If someone can help me with this, I would really appreciate it. Any hints are welcome.
Thanks.

Answer 1

this query should work :
db.user.aggregate([
{
$lookup:{
from:"userprofiles",
localField:"_id",
foreignField:"user_id",
as:"user_profile"
}
},
{
$unwind:"$user_profile"
},
{
$match:{
"user_profile.country":{
$ne:""
},
"user_profile.state":{
$ne:""
},
created_at:{
$gte: ISODate("2016-04-25T00:00:00.000Z"),
$lt: ISODate("2016-10-27T00:00:00.000Z")
}
}
},
{
$group:{
_id:null,
count:{
$sum:1
}
}
}
])
the "$group" stage is for counting results (you can't use db.col.aggregate().count()).
The output should look like
{ "_id" : null, "count" : 1 }
where "count" is the number of matching results