Mongo db - Querying nested array and objects

Question

I have the following document structure:

{
   "_id":"12345",
   "value":{
      "T":0,
      "v":[
         {
            "name":"JW",
            "cost":100
         }
      ]
   }
}

How do I query the name key? I tried the dot notation but without luck (I think it works for only two levels)

If you were by any chance doing a _group by_, you then need to use the `$unwind` operation on the `value.v` key before you can operate on the `name`/`cost` fields. — AP., Jan 06 '17 at 20:35

JohnnyHK · Answer 1 · 2014-10-27T15:17:58.257

38

It's not clear exactly what you tried, but this should work to find the above doc by name:

db.collection.find({ "value.v.name": "JW" })

Reference

edited Oct 27 '14 at 15:17

answered Jul 24 '12 at 21:50

JohnnyHK

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Thanks, i'm sure it did not work for me, maybe i got the query wrong. – karel lahmy Jul 26 '12 at 14:42
4

I don't think you can use the dot operator on an array. – Samuel O'Malley Oct 11 '13 at 02:29
2

@SamuelO'Malley I just updated the Reference link that better shows that this is supported with arrays. – JohnnyHK Oct 27 '14 at 15:19

score 20 · Answer 2 · edited Jan 06 '17 at 21:35

20

You should use $elemMatch operator:

db.collection.find({
    'value.v': { 
        $elemMatch: {
            name: 'JW', // "name == 'JW'"
            cost : 100 //if you need "&& cost == 100"
        }
    }
});

Mongo docs

edited Jan 06 '17 at 21:35

AP.

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answered Jan 26 '14 at 00:07

neftedollar

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Mongo db - Querying nested array and objects

2 Answers2

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