Update existing mongodb data into an embedded document - mongodb

Question

I am new to MongoDB so this is probably a basic question (hopefully). I currently have 10 million records with 410 fields loaded in a mongodb collection like so:
{
"_id" : ObjectId("........"),
"AddressID" : 123455,
"IndividualId" : 1,
"personfirstname" : "FirstName",
"personmiddleinitial" : "M",
"personlastname" : "LastName",
"etc": "....."
}
I need to wrap all of this data into an embedded document like so:
{
"_id" : ObjectId("........"),
"data" : {
"AddressID" : 123455,
"IndividualId" : 1,
"personfirstname" : "FirstName",
"personmiddleinitial" : "M",
"personlastname" : "LastName",
"etc": "....."
}
I don't necessarily need to update this data in-place but that would be nice. If I need to export this data somehow specifying the new format and then re-import the new, updated data that is fine. Performing this via the MongoDB shell would be ideal.

Answer 1

As suggested by chridam within comments you can execute the following aggregation pipeline:
db.collectionName.aggregate([
{ $project: { _id: "$_id", data: "$$ROOT" } },
{ $out: "newCollectionName" }
]);
This way you have the _id field both at root level and in the data object. Thus, you can execute a massive update to unset the second one:
db.newCollectionName.updateMany(
{},
{ $unset: { "data._id": "" } }
);
Finally, you can drop the first collection and rename the second to restore the original name on the updated collection:
db.collectionName.drop();
db.newCollectionName.rename("collectionName");
This approach fully works within the database, avoiding fetching any of your 10 million documents.

Answer 2

You can simply do this in the shell with the following
db.test.find().forEach(function(doc){
doc = { _id: doc._id, data: doc };
delete doc.data._id;
db.test.save(doc);
});
For example, if we insert the following documents:
> db.test.insertMany([
... {
... _id: ObjectId("5a91af8908e17c5997e03b7e"),
... field1: false,
... field2: 0,
... field3: "No"
... },
... {
... _id: ObjectId("5a91afbc08e17c5997e03b7f"),
... field1: true,
... field2: 1,
... field3: "Yes"
... }])
{
"acknowledged" : true,
"insertedIds" : [
ObjectId("5a91af8908e17c5997e03b7e"),
ObjectId("5a91afbc08e17c5997e03b7f")
]
}
Then run:
db.test.find().forEach(function(doc){
doc = { _id: doc._id, data: doc };
delete doc.data._id;
db.test.save(doc);
});
Our documents now look like this:
> db.test.find().pretty()
{
"_id" : ObjectId("5a91af8908e17c5997e03b7e"),
"data" : {
"field1" : false,
"field2" : 0,
"field3" : "No"
}
}
{
"_id" : ObjectId("5a91afbc08e17c5997e03b7f"),
"data" : {
"field1" : true,
"field2" : 1,
"field3" : "Yes"
}
}