Override existing Docs in production MongoDB

Question

I have recently changed one of my fields from object to array of objects.

In my production I have only 14 documents with this field, so I decided to change those fields.

Is there any best practices to do that?

As it is in my production I need to do it in a best way possible?

I got the document Id's of those collections.like ['xxx','yyy','zzz',...........]

my doc structure is like

_id:"xxx",option1:{"op1":"value1","op2":"value2"},option2:"some value"

and I want to change it like(converting object to array of objects)

_id:"xxx",option1:[{"op1":"value1","op2":"value2"},
                   {"op1":"value1","op2":"value2"}
                 ],option2:"some value"

Can I use upsert? If so How to do it?

Answer 1

Since you need to create the new value of the field based on the old value, you should retrieve each document with a query like

db.collection.find({ "_id" : { "in" : [<array of _id's>] } })

then iterate over the results and $set the value of the field to its new value:

db.collection.find({ "_id" : { "in" : [<array of _id's>] } }).forEach(function(doc) {
    oldVal = doc.option1
    newVal = compute_newVal_from_oldVal(oldVal)
    db.collection.update({ "_id" : doc._id }, { "$set" : { "option" : newVal } })
})

The document structure is rather schematic, so I omitted putting in actual code to create newVal from oldVal.

Answer 2

Since it is an embedded document type you could use push query

db.collectionname.update({_id:"xxx"},{$push:{option1:{"op1":"value1","op2":"value2"}}})

This will create document inside embedded document.Hope it helps