Node js query for array items in mongodb

Question

I am new in node js and I need a query for my node js script, so that it return query item from my MongoDB. What I am doing, I applying a query using node js for particular questionId which score is 1 inside MongoDB data are stored in array form, so that query will return only score's 1 questionId not score's 0.

{
"_id": "57cfc7b86f0e51ee17d4c512",
"question": [
        {
        "questionId": "57ce608e2a0d6cad8c48ef8f",
        "score": 1,
        },
        {
        "questionId": "57ce608e2a0d6cad8c48ef90",
        "score": 0,
        },
        {
        "questionId": "57ce608e2a0d6cad8c48ef91",
        "score": 0,
        }
]
}

The node js code query that i applying is I have tried two queries but they return all array items query = {'question.score':1}; query = {'question':{$eq:{'score':1}}};

function(){
             var query = {'question.score':1};
              childQuizInfo.findOne(query,function(err,data){
                        if(err) return next(err);
                        res.send(data);
                      });
                    }

I am using this query so that it return response only "questionId":"57ce608e2a0d6cad8c48ef8f", but it return all items of array.

As the array question is a field of the document, you will always get back all the content. You could not achieve this with a plain query, instead try tu use an agregation documentation — Mario Santini
– Mario Santini, Commented Sep 8, 2016 at 9:33

Dhruv · Accepted Answer · 2016-09-08 11:21:41Z

1

Use aggregation pipeline:

childQuizInfo.aggregate([{ $unwind: "$question" }, { $match: { "question.score": 1 } }, { $project: { "_id": 0, "questionId": "$question.questionId" } } ]);

Useful link:

http://excellencenodejsblog.com/mongoose-aggregation-count-group-match-project/

https://docs.mongodb.com/manual/reference/operator/aggregation-pipeline/

answered Sep 8, 2016 at 11:21

Dhruv

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Comments

shapiro yaacov · Accepted Answer · 2020-10-18 19:02:53Z

1

This will work for you:

db.getCollection('Test').aggregate([{$unwind:"$question"},{$match:{"question.score":1}}]);

edited Oct 18, 2020 at 19:02

shapiro yaacov

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answered Sep 9, 2016 at 7:44

Shantanu Madane

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