Make $elemMatch (projection) return all objects that match criteria

Question

I will use the example from here

{
 _id: 1,
 zipcode: 63109,
 students: [
              { name: \"john\", school: 102, age: 10 },
              { name: \"je         


        

Answer 1

In order to return multiple subdocuments, you're going to need to use the aggregation framework. This will return all of the subdocuments you're looking for:

db.zip.aggregate(
  {$match: {zipcode: 63109}},
  {$unwind: "$students"},
  {$match: {"students.school": 102}}
)

You can do various things to get different output, but this will return:

{
    "result" : [
        {
            "_id" : 1,
            "zipcode" : 63109,
            "students" : {
                "name" : "john",
                "school" : 102,
                "age" : 10
            }
        },
        {
            "_id" : 1,
            "zipcode" : 63109,
            "students" : {
                "name" : "jess",
                "school" : 102,
                "age" : 11
            }
        },
        {
            "_id" : 4,
            "zipcode" : 63109,
            "students" : {
                "name" : "barney",
                "school" : 102,
                "age" : 7
            }
        }
    ],
    "ok" : 1
}