Mongodb field array update

Question

I'm having a problem in updating an array in my Records table named projects->url.

Records collection

id: 1
status: "failed"
projects: Array
    0: Object
       url: www.facebook.com/testing/myprofile/1234
    1: Object
       url: www.facebook.com/testing/myprofile/12345
    2: Object
       url: www.facebook.com/testing/myprofile/123456
createdAt: Wed Dec 02 2020 16:17:26 GMT+0800
updatedAt: Wed Dec 02 2020 16:17:26 GMT+0800

id: 2
status: "passed"
projects: Array
    0: Object
       url: www.facebook.com/testing/myprofile/5
    1: Object
       url: www.facebook.com/testing/myprofile/6
    2: Object
       url: www.facebook.com/testing/myprofile/7
createdAt: Wed Dec 02 2020 16:17:26 GMT+0800
updatedAt: Wed Dec 02 2020 16:17:26 GMT+0800

This is my aggregate pipeline using map to update the array of the projects field but it doesn't update the url field.

dbo.collection('records').aggregate(
[{
    $project: 
    { 
        projects: 
        {
            $map: 
            {
                $replaceOne: { input: "$projects.url", find: "facebook", replacement: "mywebsite"}
            }
        }
    }
}]

)

I want the records projects url to be from facebook.com -> mywebsite.com

Result

Records

id: 1
status: "failed"
projects: Array
    0: Object
       url: www.mywebsite.com/testing/myprofile/1234
    1: Object
       url: www.mywebsite.com/testing/myprofile/12345
    2: Object
       url: www.mywebsite.com/testing/myprofile/123456
createdAt: Wed Dec 02 2020 16:17:26 GMT+0800
updatedAt: Wed Dec 02 2020 16:17:26 GMT+0800

id: 2
status: "passed"
projects: Array
    0: Object
       url: www.mywebsite.com/testing/myprofile/5
    1: Object
       url: www.mywebsite.com/testing/myprofile/6
    2: Object
       url: www.mywebsite.com/testing/myprofile/7
createdAt: Wed Dec 02 2020 16:17:26 GMT+0800
updatedAt: Wed Dec 02 2020 16:17:26 GMT+0800

score 1 · Accepted Answer · 2020-12-02 13:07:36Z

1

Try this, not totally sure if it's what you look for:

const pipeline= [
  {
    $addFields: {
      projects: {
        $map: {
          input: "$projects",
          as: "p",
          in: {
            "$mergeObjects": [
              "$$p",
              {
                url: {
                  "$replaceOne": {
                    "input": "$$p.url",
                    "find": "facebook",
                    "replacement": "mywebsite"
                  }
                }
              },
              
            ]
          }
        }
      }
    }
  }
]
db.collection.aggregate(pipeline)

Behaviour

If there is no match returns the same string
Returns an error if the URL is a number and not a string.
Returns url:null for missing url fields.
Merges the fields from the old object, overwriting the url.

For permanently updating original data, use

db.collection.updateMany({}, pipeline)

The variable pipeline is defined in the snippet above.

Live version

edited Dec 2, 2020 at 13:07

answered Dec 2, 2020 at 12:21

user12582392

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4 Comments

Pinky Promise Over a year ago

Hi, it is working on the live version. but when I'm applying on my database it's not updating. what seems to be the problem?

user12582392 Over a year ago

It should be outputing the documents with new data. Once that work, you can run update @PinkyPromise. Remember to replace <collection> with the actual name of the collection, and to use <yourDB> first.

Pinky Promise Over a year ago

oh it deleted the other fields and only retain my projects array.

user12582392 Over a year ago

change $project by $addFields @PinkyPromise

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