In the following code block, you can see an example of updating a single document using the update_one helper method.

This operation matches one document in the search phase and modifies one document based on the operation to be applied to the matched documents:

>>> result = books.update_one({"isbn": "101"}, {"$set": {"price": 100}})
>>> print(result.matched_count)
1
>>> print(result.modified_count)
1

In a similar way to inserting documents, when updating documents, we can use update_one or update_many:

• The first argument here is the filter document for matching the documents that will be updated
• The second argument is the operation to be applied to the matched documents
• The third (optional) argument is to use upsert=false (the default) or true, which is used to create a new document if it's not found

Another interesting argument is bypass_document_validation=false (the default) or true, which is optional. This will ignore validations (if there are any) for the documents in the collection.

The resulting object will have matched_count for the number of documents that matched the filter query, and modified_count for the number of documents that were affected by the update part of the query.

In our example, we are setting price=100 for the first book with isbn=101 through the $set update operator. A list of all update operators is displayed in the Update operators section later in this chapter.