how to convert array to object in MongoDB

Question

I have an array of object as given with unknown number of array elements:

               { "content": [
                    {
                        "_id": "refbooks",
                        "total": 189,
                        "published": 189,
                        "created": 0,
                        "approved": 0,
                        "rejected": 0,
                        "sent_for_approval": 0
                    },
                    {
                        "_id": "weblinks",
                        "total": 1911,
                        "published": 1899,
                        "created": 10,
                        "approved": 2,
                        "rejected": 0,
                        "sent_for_approval": 0
                    },.................]}

I want to convert it to an object like given:

                    { "content": {
                    {
                        "_id": "refbooks",
                        "total": 189,
                        "published": 189,
                        "created": 0,
                        "approved": 0,
                        "rejected": 0,
                        "sent_for_approval": 0
                    },
                    {
                        "_id": "weblinks",
                        "total": 1911,
                        "published": 1899,
                        "created": 10,
                        "approved": 2,
                        "rejected": 0,
                        "sent_for_approval": 0
                    },.................}}

I tried using $unwind, but I did't get my required output. How to implement this inside aggregation pipeline in MongoDB?

I'm using Mongo version 3.4.

That's an impossible setup... Not sure what you mean. Whenever you have a collection of things it has to be wrapped in an array...? — dnickless
– dnickless, Commented Oct 25, 2018 at 11:34

Labeeb Shareef · Accepted Answer · 2018-10-26 06:23:41Z

18

I found the solution.

{
            $project: {
                "content": {
                    "$arrayToObject": {
                        "$map": {
                            "input": "$content",
                            "as": "el",
                            "in": {
                                "k": "$$el._id",
                                "v": "$$el"
                            }
                        }
                    }
                }
}

answered Oct 26, 2018 at 6:23

Labeeb Shareef

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Comments

shivam dhankani · Accepted Answer · 2018-10-25 11:58:25Z

0

I guess the second one is not a proper object format you need a key value pare for make object

{ "content": {
                   "key1":{
                        "_id": "refbooks",
                        "total": 189,
                        "published": 189,
                        "created": 0,
                        "approved": 0,
                        "rejected": 0,
                        "sent_for_approval": 0
                    },
                   "key2":{
                        "_id": "weblinks",
                        "total": 1911,
                        "published": 1899,
                        "created": 10,
                        "approved": 2,
                        "rejected": 0,
                        "sent_for_approval": 0
                    }}}

answered Oct 25, 2018 at 11:58

shivam dhankani

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2 Comments

Labeeb Shareef Over a year ago

Yeah, like that

shivam dhankani Over a year ago

@LabeebShareef i guess you already find the answer there is another way for doing same by using underscore.js underscorejs.org/#groupBy

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