Why does upsert a record using update_one raise ValueError?
This is because you didn't specify any update operator.For example to $set the id value use:
db.collection.update_one({"_id":"key1"}, {"$set": {"id":"key1"}}, upsert=True)Note that in the Mongo shell, this will simply replace the document with the new document.
Use replace_one() instead of update_one(). the 3rd parameter of replace_one() is upsert, too.
db.collection.replace_one({"_id": "key1"}, {"_id": "key1"}, True) My personal opinion is this implementation of update_one() is inconsistent with the behaviour of MongoDB client. The upsert option in update_one() is actually meaningless. But the developers of pyMongo may just want to use this to distinguish update_one() and replace_one().