Querying MongoDB collection having array of JSON documents

Question

I have a mongodb collection in the format:

    {
    _id:"xxxx"
    comments : [
            {
                comment:"I know good art is supposed to be controversial"
                commentid:"820168"
                username:"bleckfella"
                isprocessed:0
            },
            {
                comment:"Next thing.."
                commentid:"820846"
                username:"egzegs"
                isprocessed:0
            },
            {
                comment:"Good decision, please stay away Jamie."
                commentid:"820901"
                username:"Capt_mulch"
                isprocessed:1
            }
        ]

    some fields.....
    ....
    ....
}
{
    _id:"xxxx"
    comments : [
            {
                comment:"who REALLY cares?"
                commentid:"820162"
                username:"BigBunny"
                isprocessed:0
            },
            {
                comment:"Double oh dear ..."
                commentid:"820849"
                username:"MrX"
                isprocessed:1
            },
            {
                comment:"Good decision."
                commentid:"830501"
                username:"mark11"
                isprocessed:0
            }
        ]

    some fields.....
    ....
    ....
}
{
        _id:"xxxx"
    comments : [
            {
                comment:"my condolences Mick. My thoughts are with you."
                commentid:"821164"
                username:"BigBunny"
                isprocessed:0
            },
            {
                comment:"Three letters.     O. M. G."
                commentid:"840844"
                username:"MrX"
                isprocessed:0
            }

        ]

    some fields.....
    ....
    ....
}

Now I want to query this data for comments having value of "isprocessed" field as "1" The queries I have tried from shell are :

db.coll.find({comments:{$elemMatch: {isProcessed:1}}},{"comments.isProcessed":1,"comments.comment":1}).pretty()

&

db.coll.find({"comments.isProcessed":1},{"comments.isProcessed":1,"comments.comment":1}).pretty()

Both are giving the same output which is:

{
    _id : "xxxx"
    "comments : [
            {
                comment:"I know good art is supposed to be controversial"
                isprocessed:0
            },
            {
                comment:"Next thing.."
                isprocessed:0
            },
            {
                comment:"Good decision, please stay away Jamie."
                isprocessed:1
            }
        ]

}
{
    _id : "xxxx"
    comments : [
            {
                comment:"who REALLY cares?"
                isprocessed:0
            },
            {
                comment:"Double oh dear ..."
                isprocessed:1
            },
            {
                comment:"Good decision."
                isprocessed:0
            }
        ]

}

Means it is showing the comments with "isprocessed" field value "0" for matched document which I dont need. I need the output as :

{
    "_id":"xxxx"
    comments : [
            {
                comment:"Good decision, please stay away Jamie."
                isprocessed:1
            }
        ]
}
{
    _id:"xxxx"
    comments : [
            {
                comment:"Double oh dear ..."
                isprocessed:1
            }
        ]
}

I also need to update the value of field "isprocessed" after reading it in this format. How to write a query for that. Plz suggest any solution.

dikesh · Accepted Answer · 2014-04-03T12:37:12.907

0

try following command

db.coll.aggregate([{$unwind: '$comments'}, {$match : {'comments.isprocessed' : 1}}, {$project : {_id : 1, 'comments.comment' : 1, 'comments.isprocessed' : 1}}])

edited Apr 03 '14 at 12:37

answered Apr 03 '14 at 12:27

dikesh

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It has worked. Thanks a lot Dikesh. But one more question. How to change this isprocessed field to 0 from one using a query. – user2710961 Apr 03 '14 at 13:08
means you want to print records where value of isprocessed is 0. right? – dikesh Apr 03 '14 at 13:10
No, I want to update the value of isprocessed field from 1 to 0 in database. – user2710961 Apr 03 '14 at 13:25
This answer will be able to help you. http://stackoverflow.com/questions/10522347/mongodb-update-an-object-in-nested-array – dikesh Apr 03 '14 at 13:30

Querying MongoDB collection having array of JSON documents

1 Answers1