MongoDB $match not working for part of sub document - mongodb

Question

In my MongoDB, I am trying to "group by" a set of records using the aggregate() function and the $match query I use does not select the records in the pipeline.
My dataset has sub documents (on which I apply the $match) and it looks like this:
{
"_id" : ObjectId("550994e21cba9597624195aa"),
"taskName" : "task name",
"taskDetail" : "task detail.",
"scheduledStartDate" : ISODate("2015-04-06T09:00:00.000Z"),
"scheduledEndDate" : ISODate("2015-04-06T11:00:00.000Z"),
"user" : {
"id" : "abcd1123",
"name" : "username"
},
"status" : "Assigned"
}
{
"_id" : ObjectId("550994e21cba9597624195aa"),
"taskName" : "task name",
"taskDetail" : "task detail.",
"scheduledStartDate" : ISODate("2015-04-06T09:00:00.000Z"),
"scheduledEndDate" : ISODate("2015-04-06T11:00:00.000Z"),
"user" : {
"id" : "abcd1123",
"name" : "username"
},
"status" : "Assigned"
}
{
"_id" : ObjectId("550994e21cba9597624195aa"),
"taskName" : "task name",
"taskDetail" : "task detail.",
"scheduledStartDate" : ISODate("2015-04-06T09:00:00.000Z"),
"scheduledEndDate" : ISODate("2015-04-06T11:00:00.000Z"),
"user" : {
"id" : "abcd1124",
"name" : "username"
},
"status" : "Assigned"
}
I want to find out count of status for a particular user grouped by status type. For the user "abcd1123", the query that I use is:
db.tasks.aggregate( [
{
$match : {
user : { id : "abcd1123" }
}
},
{
$group: {
_id: "$status",
count: { $sum: 1 }
}
}
] )
The above query does not return any results, because the $match does not put any results into the pipeline. If I modify the query like this:
db.tasks.aggregate( [
{
$match : {
user : { id : "abcd1123", name : "username" }
}
},
{
$group: {
_id: "$status",
count: { $sum: 1 }
}
}
] )
it works. But I don't have the username as input and I need to find only based on user id.
Since user is not an array, I can't use $unwind on it.
How do I acheive this?

Answer 1

You are too close only change your aggregation query as below
db.collectionName.aggregate({
"$match": {
"user.id": "abcd1123"
}
},
{
"$group": {
"_id": "$status",
"count": {
"$sum": 1
}
}
})