Group By year-month

Working with Data Node.js Frameworks
, ,
6

You can use this aggregate to start with and refine it as per your formatting:

db.collection.aggregate([
{ 
    $match: { _id: INPUT_USER_ID } 
},
{ 
    $group: {
        _id: { year: { $year: "$date_started" }, month: { $month: "$date_started" } },
        total_cost_month: { $sum: "$total_cost" }
    }
}
])

A sample output for a year+month would be:

{ 
  "_id" : { "year" : 2021, "month" : 6 }, 
  "total_cost_month" : 16.8 
}