How to group by and count with mongodb?

Question

I am trying to group by and count with mongodb. Whatever I tried I couldn't do it. This is my query

db.getCollection("requests").find(
    {
        "updatedAt" : {
            "$gt" : ISODate("2020-05-14")
        },
        "status" : "SUGGESTED"
    },
    {
        "user.email" : 1.0,
        "user.name" : 1.0,
        "updatedBy.displayName" : 1.0,
        "requestTerm" : 1.0
    }
)

I would like to group and count based on updatedBy.displayName

So result will be for me distinct displayname ( Column1), count ( number of times )

How can I achieve this?

This is what I tried and it seems it doesn't work

db.requests.aggregate(
    {$match: {         "updatedAt" : {
            "$gt" : ISODate("2020-05-14")
        },
        "status" : "SUGGESTED" }},
    {$group: {updatedBy: "$updatedBy.displayName", number: {$sum: 1}}}
)

Answer 1

According to the mongo manual on $group, the command should be like this.

db.requests.aggregate(
    [
        {$match: {         
                "updatedAt" : {"$gt" : ISODate("2020-05-14")},
                "status" : "SUGGESTED" 
        }},
        {$group: {
            _id: {updatedBy: "$updatedBy.displayName"}, 
            number: {$sum: 1}
        }}
    ]
)