In MongoDb, how to apply sort internal fields present in document?

Question

My document looks like this

{
  field1: somevalue,
   name:xtz


  nested_documents: [ // array of nested document
    { x:"1", y:"2" }, // first nested document
    { x:"2", y:"3" }, // second nested document
    { x:"-1", y:"3" }, // second nested document
    // ...many more nested documents
  ]
}

How one can sort the data present in nested_documents?
Expected answer is shown below:

nested_documents: [ { x:"-1", y:"3" },{ x:"1", y:"2" },{ x:"2", y:"3" }]

This might actually be faster in your client code to than using the aggregation framework, depending on the size of your subdocuments of course. — Sammaye, Mar 08 '13 at 13:25

score 1 · Answer 1 · answered Mar 08 '13 at 10:18

To do this you would have to use the aggregation framework

db.test.aggregate([{$unwind:'$nested_documents'},{$sort:{'nested_documents.x': 1}}])

this returns

"result" : [
    {
            "_id" : ObjectId("5139ba3dcd4e11c83f4cea12"),
            "field1" : "somevalue",
            "name" : "xtz",
            "nested_documents" : {
                    "x" : "-1",
                    "y" : "3"
            }
    },
    {
            "_id" : ObjectId("5139ba3dcd4e11c83f4cea12"),
            "field1" : "somevalue",
            "name" : "xtz",
            "nested_documents" : {
                    "x" : "1",
                    "y" : "2"
            }
    },
    {
            "_id" : ObjectId("5139ba3dcd4e11c83f4cea12"),
            "field1" : "somevalue",
            "name" : "xtz",
            "nested_documents" : {
                    "x" : "2",
                    "y" : "3"
            }
    }
],
"ok" : 1

Hope this helps

Thanks for reply. But, I want only one object with elements inside nested_documents sorted — Sachin, Mar 09 '13 at 16:45

In MongoDb, how to apply sort internal fields present in document?

1 Answers1

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