How to push a field's value into another array field of same doc in MongoDB update

Question

I have one mongodb object like below :

{
    "_id" : ObjectId("5e54934b2dfddc1826223bbb"),
    "sellProducts" : {
        "products" : []
    },
    "sellServices" : {
        "services" : []
    },
    "categories" : [],
    "status" : "Published",
    "tags" : [],
    "dateRange" : [],
    "membershipRequired" : false,
    "usersAttending" : [],
    "cities" : [],
    "companies" : [ 
        ObjectId("5db1c84ec10c45224c4b95fd"),
    ],
    "companyId" : ObjectId("5db1c84ec10c45224c4b95fd"),
    "jobProfile" : [ 
        ObjectId("5e549339a3ad20c97b7b0c7d")
    ],
    "fundingBy" : []
}

Now I want to update the same record by pushing the value of the companyId field into the array of companies. How can I do that?

I tried below query but It didn't work :

db.getCollection('posts').update({_id: ObjectId("5e54934b2dfddc1826223bbb")},
    {
        $push: 
            {
                companies: "$$companyId"
            }
    })

@mehta-rohan, I update the question. It's companyId not a company. — Jay Sojitra, Apr 16 '20 at 17:32
Does this answer your question? [Update MongoDB field using value of another field](https://stackoverflow.com/questions/3974985/update-mongodb-field-using-value-of-another-field) — whoami - fakeFaceTrueSoul, Apr 16 '20 at 17:34
@whoami, No this question is a little bit different. They concat two strings, I want to push the value to an array. — Jay Sojitra, Apr 17 '20 at 03:46
@JaySojitra : If you get the concept it would be easy !! It's not about concatenation of two strings or pushing value that question about using existing field value in document while updates - So which is exactly same !! Please read and try it if not let us know... — whoami - fakeFaceTrueSoul, Apr 17 '20 at 03:51
@whoami, I tried [this link](https://stackoverflow.com/questions/3788256/mongodb-updating-documents-using-data-from-the-same-document/3792958#3792958), but somehow It won't work. — Jay Sojitra, Apr 17 '20 at 03:58
Also @whoami, I am trying to update this from robo3t console itself. — Jay Sojitra, Apr 17 '20 at 04:00

score 3 · Accepted Answer · answered Apr 17 '20 at 04:27

3

As you're using MongoDB version 4.2 where you can actually run aggregation pipeline in updates, Try below query :

/** As `$push` doesn't work in aggregation as update operator
 * You can use `$addFields` or `$set` to re-create 'companies' field by merging 'companies' array with array converted 'companyId' field
 * which would leave 'companies' as an array with existing elements + companyId */

db.getCollection('posts').updateOne({_id: ObjectId("5e54934b2dfddc1826223bbb")},
         [{$addFields : {companies: {$concatArrays: ['$companies',['$companyId']]}}}])

answered Apr 17 '20 at 04:27

whoami - fakeFaceTrueSoul

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1

Thank you for your support. But when I execute your script it gives me below error: "Failed to execute script. Error: the update operation document must contain atomic operators Details:" – Jay Sojitra Apr 17 '20 at 06:41
3

@JaySojitra : In the past I’ve observed robo3T has issues using aggregation pipeline in updates especially with updateMany() & updateOne(), just try with update() !! – whoami - fakeFaceTrueSoul Apr 17 '20 at 06:43

How to push a field's value into another array field of same doc in MongoDB update

1 Answers1