MongoDb upsert exception invalid BSON field

updateOne for updating document fields using update operators. You need replaceOne which takes the replacement document.

_collection.replaceOne(        trackID,        track,        new UpdateOptions().upsert( true ));

More here

Update Operators: https://docs.mongodb.com/manual/reference/operator/update-field/

Update One:https://docs.mongodb.com/manual/reference/method/db.collection.updateOne/

Replace One: https://docs.mongodb.com/manual/reference/method/db.collection.replaceOne/

Another option is setOnInsert, as shown in the document of MongoDB:

https://docs.mongodb.com/manual/reference/operator/update/setOnInsert/

The operation works only when upsert is true.

In your case, you should put fields not to be modified in a document, and fields to be updated in another document, and in the third document, prepend $setOnInsert and $set as key, respectively.

A big advantage of $setOnInsert is that when inserting, it will perform $setOnInsert and $set part, but when updating, only $set will be executed.

For example, we have a document to insert/update, which has 5 fields: name, age, gender, createAt, updateAt.

• When I do a query by field "name" and find no match, I want to insert the document with 5 fields, and fill createAt and updateAt with current datetime.
• When I do a query by "name" and find a match, I want to update name and updateAt with current datetime.

What I do is:

query = Filters.eq("name", nameToSearch);Document upsert = new Document();Date now = new Date();//only fields not mentioned in "$set" is needed hereDocument toInsert = new Document()        .append("age", newAge)        .append("gender", genderString)        .append("createAt", now);//the fields to update here, whether on insert or on update.Document toUpdate = new Document().append("name", nameToSearch)        .append("updateAt", now);//will: // - insert 5 fields if query returns no match// - updates 2 fields if query returns matchupsert.append("$setOnInsert", toInsert)        .append("$set", toUpdate);UpdateResult result = collection.updateOne(query, toUpdate,     new UpdateOptions().upsert(true));