how filter inside array in mongodb - mongodb

Question

I want to filter only kumar "to" items"_id" : ObjectId("5048d2e5fbdac48208000042") message from my query and expected result
{
"_id" : ObjectId("5191502a2f1b3ca33e000016"),
"message" : "<p>sssdasd<br></p>",
"subject" : "test message to nag",
"date" : ISODate("2013-05-13T20:42:19.349Z")
}
from below collections
{
"__v" : 0,
"_id" : ObjectId("5191502a2f1b3ca33e000016"),
"conversation" : [
{
"date" : ISODate("2013-05-13T20:42:19.349Z"),
"message" : "<p>sssdasd<br></p>",
"_id" : ObjectId("5191502a2f1b3ca33e000017"),
"to" : {
"_id" : ObjectId("5048d2e5fbdac48208000042"),
"name" : "Kumar"
},
"from" : {
"_id" : ObjectId("503fdbfa294f6db74de649ea"),
"name" : "Anand"
}
},
{
"message" : "<p>reply</p>",
"date" : ISODate("2013-05-13T21:05:33.453Z"),
"_id" : ObjectId("5191559c7d2c386741000018"),
"to" : {
"_id" : ObjectId("503fdbfa294f6db74de649ea"),
"name" : "Anand"
},
"from" : {
"_id" : ObjectId("5048d2e5fbdac48208000042"),
"name" : "Kumar"
}
},
{
"message" : "<p>reply2<br></p>",
"date" : ISODate("2013-05-13T21:05:55.006Z"),
"_id" : ObjectId("519155b1ca98b66641000014"),
"to" : {
"_id" : ObjectId("503fdbfa294f6db74de649ea"),
"name" : "Anand"
},
"from" : {
"_id" : ObjectId("503fdbfa294f6db74de649ea"),
"name" : "Anand"
}
}
],
"from" : {
"_id" : ObjectId("503fdbfa294f6db74de649ea"),
"name" : "Anand"
},
"sent" : ISODate("2013-05-13T20:42:19.349Z"),
"subject" : "test message to nag",
"to" : {
"_id" : ObjectId("5048d2e5fbdac48208000042"),
"name" : "Kumar"
}
}
I was try with below query
db.messages.find({'conversation.to._id':ObjectId("5048d2e5fbdac48208000042")},{'subject':-1, 'conversation.message': 1,'conversation.to':1}).pretty();
But I am not get the expected result

Answer 1

I have used aggregate framework I am able to get the expected result.
db.message.aggregate(
{ $unwind : "$conversation" },
{ $match: {
"conversation.to.name" : "Anand"
}
},
{
$sort: {
"conversation.date" : -1
}
},
{
$group: {
_id:"$_id",
msgSubject: {$first:"$subject"},
msgDate: {$first:"$conversation.date"},
latestmsg: {$first:"$conversation.message"}
}
}
);
Please share if any different than above