How can i find object from an array in mongoose

Question

I have a schema like following : -

var P = {
     s : [{
         data : [],
         sec : mongoose.Schema.Types.ObjectId
     }]
 };

Now I want to find only the object of section not entire the row. Like If I pass sec value I want only the value of s.data of that sec object.

example : -

{ s : [ 
    {
       data : [],
       sec : '52b9830cadaa9d273200000d'
    },{
        data : [],
       sec : '52b9830cadaa9d2732000005'
    }
  ]
}

Result should be look like -

 {
    data : [],
    sec : '52b9830cadaa9d2732000005'
 }

I do not want all entire row. Is it possible? If yes, then please help me.

JohnnyHK · Accepted Answer · 2013-12-26 16:29:15Z

14

You can use the $elemMatch projection operator to limit an array field like s to a single, matched element, but you can't remove the s level of your document using find.

db.test.find({}, {_id: 0, s: {$elemMatch: {sec: '52b9830cadaa9d2732000005'}}})

outputs:

{
  "s": [
    {
      "data": [ ],
      "sec": "52b9830cadaa9d2732000005"
    }
  ]
}

edited Dec 26, 2013 at 16:29

answered Dec 26, 2013 at 15:53

JohnnyHK

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Comments

Workonphp · Accepted Answer · 2013-12-26 14:05:34Z

0

You can always get the value of some field by using find(). For example in your case:

db.collectionName.find({},{s.data:1})

So the first bracket is to apply any condition or query, and in the second bracket you have to define the field as 1(to fetch only those fields value).

Please check http://docs.mongodb.org/manual/reference/method/db.collection.find for more information. Let me know if it solves your problem.

answered Dec 26, 2013 at 14:05

Workonphp

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1 Comment

Kundu Over a year ago

Thanks for your reply. Your answer give me the whole array. But I want only the particular object of the array. If you have any suggestion reply me.

BetaCoder · Accepted Answer · 2013-12-26 15:22:03Z

Not into Mongo or db but working with Pure JavaSript skills here is the Solution as you mentioned Node.js which would do the execution task of the below.

Schema

   var P = { s : [ 
            {
             data : [],
             sec : '52b9830cadaa9d273200000d'
              },{
             data : [],
             sec : '52b9830cadaa9d2732000005'
              }
         ]
    };

Search Method Code

var search = function (search_sec){
     for (var i=0; i<(P.s.length);i++){

       var pointer = P.s[i].sec;
       var dataRow = P.s[i];

        if((pointer) === search_sec ){

             console.log(dataRow);

          }
      }

};

Here is How you can call - search('search_id');

For example input : search('52b9830cadaa9d2732000005');

Output:

 [object Object] {
                  data: [],
                  sec: "52b9830cadaa9d2732000005"
                  }

Working Demo here - http://jsbin.com/UcobuVOf/1/watch?js,console

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