MongoDB update all document using JavaScript

Question

Suppose I have collection with following data.

{
     _id: ObjectID(....),
     ...
     data : [ 23, 34]
}

I have following JavaScript function.

function reduce(array){
    //some computation
    return result; // not array
}

Is there any way to update all the collection using MongoDB shell with following net effect.

{
    data : reduce(data)
}

Edit:

I am looking to execute this for only one time as part of migration.

You can make use of stored functions: docs.mongodb.org/manual/tutorial/… — ZeMoon
– ZeMoon, Commented Apr 3, 2015 at 8:26
I am looking to execute this for only one time as part of migration. — Pavan Kumar
– Pavan Kumar, Commented Apr 3, 2015 at 9:57

Leonid Beschastny · Accepted Answer · 2015-04-03 10:20:22Z

1

Sure, you could iterate over MongoDB cursor using cursor.forEach() method and saving processed documents with db.collection.save() method, e.g.:

db.collection.find().forEach(function(doc) {
  doc.data = reduce(doc.data); // update field
  db.collection.save(doc); // save
})

answered Apr 3, 2015 at 10:07

Leonid Beschastny

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