Database
[{
"name": "John Snow",
"category": 1
}, {
"name": "Jason Statham",
"category": 2
}, {
"name": "John Lennon",
"category": 2
}, {
"name": "John Snow",
"category": 3
}]
Query
db.collection.aggregate([{
"$match": {
"name": {
"$regex": "john",
"$options": "i"
}
}
}, {
"$group": {
"_id": "$name",
"category": {
"$first": "$category"
}
}
}])