How to use upsert - mongodb

Question

I have collection with documents like this
[
{ _id : ObjectId("xxxxxx") , u_id : 5 , name : "E" , comment : [1,2] },
{ _id : ObjectId("yyyyyy") , u_id : 4 , name : "D" , comment : [] },
{ _id : ObjectId("zzzzzz") , u_id : 3 , name : "C" , comment : [1,2] },
{ _id : ObjectId("aaaaaa") , u_id : 2 , name : "B" , comment : [1,2] },
{ _id : ObjectId("bbbbbb") , u_id : 1 , name : "A" , comment : [1] },
]
Now I have an array of documents prepare to Insert or Update to this collection like this
var multi_document =
[
{ u_id : 8 , name : "H" , comment : [1,2] }, //Insert new document
{ u_id : 7 , name : "G" , comment : [] }, //Insert new document
{ u_id : 6 , name : "F" , comment : [1,2] }, //Insert new document
{ u_id : 5 , name : "E" , comment : [1,2,3] }, //update [1,2] to [1,2,3]
{ u_id : 4 , name : "DD" , comment : [1] }, //update D to DD and [] to [1]
{ u_id : 3 , name : "C" , comment : [1,2] }, //not do anything it same original
];
Can I use db.collection.update(multi_document); ? If not , What should I do?
This is the expected result:
[
{ _id : ObjectId("db_created") , u_id : 8 , name : "H" , comment : [1,2] },
{ _id : ObjectId("db_created") , u_id : 7 , name : "G" , comment : [] },
{ _id : ObjectId("db_created") , u_id : 6 , name : "F" , comment : [1,2] },
{ _id : ObjectId("xxxxxx") , u_id : 5 , name : "E" , comment : [1,2,3] },
{ _id : ObjectId("yyyyyy") , u_id : 4 , name : "DD" , comment : [1] },
{ _id : ObjectId("zzzzzz") , u_id : 3 , name : "C" , comment : [1,2] },
{ _id : ObjectId("aaaaaa") , u_id : 2 , name : "B" , comment : [1,2] },
{ _id : ObjectId("bbbbbb") , u_id : 1 , name : "A" , comment : [1] },
]

Answer 1

The best way to do this is using the "Bulk" API.
First you need to loop over your multi_document array and for each document find in your collection, documents with same u_id. To that we need to use the bulk.find.upsert method which sets the upsert to true and then use the .update method which specifies the fields to update, here comment. In the update document you need to use the $addToSet operator to ensure that there are not duplicate in your comment field and the $each modifier because comment is an array.
var bulk = db.collection.initializeOrderedBulkOp(),
count = 0;
multi_document.forEach( function (doc) {
bulk.find({ "u_id": doc.u_id })
.upsert()
.update({
"$set": { "name": doc.name },
"$addToSet": { "comment": { "$each": doc.comment }}
});
count++;
if ( count % 1000 == 0 ) {
// Execute per 1000 operations and re-init.
bulk.execute();
bulk = db.collection.initializeOrderedBulkOp();
}
})
// Clean up queues
if ( count % 1000 != 0 )
bulk.execute();

Answer 2

You could use Bulk() http://docs.mongodb.org/manual/reference/method/Bulk/
With an ordered operations list, MongoDB executes the write operations in the list serially. If an error occurs during the processing of one of the write operations, MongoDB will return without processing any remaining write operations in the list.
Interesting Blog Article about the Bulk API: http://blog.mongodb.org/post/84922794768/mongodbs-new-bulk-api