How to prevent duplication in update statement

January 31, 2023

I have documents like this in my MongoDB collection:

my_dict = {"chat": 1, "entity": 2, "count": 55}

I need to update them and if the document does not exist (entirely), then insert a new one:

results_collection.update_one(my_dict,
                    {"$set": {"chat": 1,
                              "entity": 2,
                              "count": 60}},
                    upsert=True)

But if the document exists, it is duplicating it! it should just update because chat and entity are the same. But it is inserting a new one.
So, I will be having two similar documents with differences in count only.

See how this is duplicated in the picture ,

I want the new one to replace the above one.

How can I do that?

>Solution :

You need to find the matching document. In your case, you can do it by the identical fields:

results_collection.update_one({'chat': my_dict['chat'], 'entity': my_dict['entity']},
                    {"$set": {"chat": 1,
                              "entity": 2,
                              "count": 60}},
                    upsert=True)

The code in the original question is using my_dict to try to find the matching document to update, but my_dict includes the count, thus never finds the document and thus creating a new one…