Mongo complex aggregate (condition based on group count) - mongodb

Question

Id need a mongo aggregate that given the sample data:
{
'employeeNumber': '1',
'companyId': '1',
'role': 'D',
'dateHired':ISODate("2013-11-26T00:00:00.0Z")
...
}
{
'employeeNumber': '1',
'companyId': '1',
'role': 'S',
'dateHired':ISODate("2013-11-26T00:00:00.0Z")
...
}
{
'employeeNumber': '1',
'companyId': '2',
'role': 'D',
'dateHired':ISODate("2013-11-26T00:00:00.0Z")
...
}
{
'employeeNumber': '2',
'companyId': '1',
'role': 'D',
'dateHired':ISODate("2013-11-26T00:00:00.0Z")
...
}
queries for a given companyId (e.g. companyId = 1, using match stage probably) and would return something like:
{
'employeeNumber': '1',
'companyId': '1',
'role': 'D','S'
'dateHired':ISODate("2013-11-26T00:00:00.0Z")
...
}
notice that
{
'employeeNumber': '1',
'companyId': '2',
'role': 'D'
'dateHired':ISODate("2013-11-26T00:00:00.0Z")
...
}
is not returned.
Ideally it would return the whole object as the collection has 10/12 fields.

Answer 1

By using aggregation you will not get exact expected output but you can get output like following:
{ "role" : [ "D" ], "employeeNumber" : "2" }
{ "role" : [ "S" ], "employeeNumber" : "3" }
{ "role" : [ "D", "S" ], "employeeNumber" : "1" }
And the query will be like:
db.collection.aggregate({
$group: {
_id: "$employeeNumber",
"role": {
"$push": "$role"
}
}
}, {
$project: {
"employeeNumber": "$_id",
"role": 1,
"_id": 0
}
})
Edit After question edit:
db.collection.aggregate({
$group: {
_id: {
employeeNumber: "$employeeNumber",
"companyId": "$companyId"
},
"role": {
"$push": "$role"
},
"dateHired": {
$last: "$dateHired"
}
}
}, {
$project: {
"employeesNumber": "$_id.employeeNumber",
"comapnyId": "$_id.companyId",
"role": 1,
"dateHired": 1,
"_id": 0
}
})