Definition
MongoDB\UpdateResult::getModifiedCount()Return the number of documents that were modified.
function getModifiedCount(): integer|null This method should only be called if the write was acknowledged.
Note
If an update/replace operation results in no change to the document (e.g. setting the value of a field to its current value), the modified count may be less than the value returned by
getMatchedCount().
Return Values
The number of documents that were modified.
Errors/Exceptions
MongoDB\Exception\BadMethodCallException if this method is called and the write operation used an unacknowledged write concern.