How to filter and map array of documents in MongoDB query?

Question

So I\'ve got these documents in my people collection:

{
        \"_id\" : ObjectId(\"595c0630939a8ae59053a9c3\"),
        \"name\" : \"John Smith\",
                 


        

Answer 1

You can wrap the $filter expression inside $map to map the output values.

db.people.aggregate([
  {
    "$project": {
      "name": 1,
      "age": 1,
      "hobbies": {
        "$map": {
          "input": {
            "$filter": {
              "input": "$hobbies",
              "as": "hobbyf",
              "cond": "$$hobbyf.regular"
            }
          },
          "as": "hobbym",
          "in": {
            "name": "$$hobbym.name",
            "type": "$$hobbym.type"
          }
        }
      }
    }
  }
])