如何复制mongodb文档，然后更新字段的值

Question

I would like to copy an existing document and will give it a new objectID, and then update a field of newly added document.

Currently, I am using "find" to get a collection of documents, and iterating the list, then use insertOne and updateOne to insert a new document and update the field value. But it seems like the field value that get updated is belong to the document with old object id. And I want the field value belong to the document with new ObjectID get updated.

myDocList = collection.find(new Document("track", trackName));  

for (Document document : myDocList) {
    collection.insertOne(new Document(document));
    collection.updateOne(new Document("track", trackName), new Document("$set", new Document("track", newTrackName)));
     System.out.println(document);
}

Answer 1

Why don't you change your new Document before inserting?

for (Document document : myDocList) {
    Document doc = new Document(document);
    doc.setTrackName(newTrackName); // or doc.put("track", newTrackName); if your doc implements Map
    collection.insertOne(doc);
    System.out.println(document);
}

of course updateOne method will update first found record with that trackName. If you need to save your logic, you need somehow to save objectId of new Document inserted. And then call update object by objectId. Something like:

for (Document document : myDocList) {
    collection.insertOne(new Document(document)).getObjectId(); //save this value
    //I don't know exactly which mongo driver do you use
    collection.updateOne(new Document("_id", savedObjId), new Document("$set", new Document("track", newTrackName)));
     System.out.println(document);
}