How to return match document by using $in operator for array of object

Question

may I know how can I use $in operator for array of object? and only return match document as result?

This is what I have tried so far but I still not able to get what I want.

Let's say I have set of documents look like this

{
    "_id" : ObjectId("56824417fa32883c0335ce61"),
    "company_name" : "Pentagon",
    "deal_details" : [
        {
            "deals_name" : "hello",
            "deals_tag" : ["A","B","C"],
            "_id" : ObjectId("56c69da8a1f60804064abf0f")
        },
    {
            "deals_name" : "Hola",
            "deals_tag" : ["E","F","G"],
            "_id" : ObjectId("56c69da8a1f60804064abf0f")
        },
    ],
  "_id" : ObjectId("54824417fa32983c0335ce61"),
    "company_name" : "Oreo",
    "deal_details" : [
        {
            "deals_name" : "Bye",
            "deals_tag" : ["B"],
            "_id" : ObjectId("56c69da8a1f60804064abf0f")
        },
    {
            "deals_name" : "Ciao",
            "deals_tag" : ["H","I","J"],
            "_id" : ObjectId("56c69da8a1f60804064abf0f")
        },
    ]
}

and I do this

User.find({
  'deal_details.deals_tags': {
    $in: ["B"]
  }
 }
}, {'deal_details':1}).exec(function(err, deal) {
  if (err) {
    return res.status(500).send(err);
  }
  res.status(200).send(deal);
});

what I expect from deal is

            {
                "deals_name" : "hello",
                "deals_tag" : ["A","B","C"],
                "_id" : ObjectId("56c69da8a1f60804064abf0f")
            },
             {
                "deals_name" : "Bye",
                "deals_tag" : ["B"],
                "_id" : ObjectId("56c69da8a1f60804064abf0f")
            }

however I get this instead

            {
                "deals_name" : "hello",
                "deals_tag" : ["A","B","C"],
                "_id" : ObjectId("56c69da8a1f60804064abf0f")
            },
            {
                "deals_name" : "Hola",
                "deals_tag" : ["E","F","G"],
                "_id" : ObjectId("56c69da8a1f60804064abf0f")
            },
             {
                    "deals_name" : "Bye",
                    "deals_tag" : ["B"],
                    "_id" : ObjectId("56c69da8a1f60804064abf0f")
             },
             {
            "deals_name" : "Ciao",
            "deals_tag" : ["H","I","J"],
            "_id" : ObjectId("56c69da8a1f60804064abf0f")
             }

So can I know is there a way to only return only matched document? your help is appreciated thanks!

zangw · Accepted Answer · 2016-02-22 13:16:15Z

2

You could do that through aggregation

User.aggregate([{$unwind: '$deal_details'}, 
                {$match: {'deal_details.deals_tag': 'B'}}, 
                {$project: {deal_details: 1, _id: 0}}])

answered Feb 22, 2016 at 13:16

zangw

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2 Comments

John Lim Over a year ago

Hi @zangw thanks for your reply, may I know is it possible to use $in in $match in order to match more document? like ['B','H'] and then return match document

zangw Over a year ago

@JohnLim, yes, you can do that as {$match: {'deal_details.deals_tag': {$in: ['B', 'H']}}}

Community · Accepted Answer · 2017-05-23 11:50:34Z

2

To find elements with specific value in array in sub Document (it's your case) and to filter the result, you shoul use the aggregation framework. It's impossible with a simple find document.

You can see an example with your problem here : How to filter array in subdocument with MongoDB

edited May 23, 2017 at 11:50

CommunityBot

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answered Feb 22, 2016 at 12:57

throrin19

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