Boto3 updating multiple values
Yes, that's the way to do. Even many actions can be done in single expression as shown here. For ex: multiple 'PUT' and 'DELETE' in single expression.
For others finding this, theres a library you can use to help with the weird boto3 stuff like ExpressionAttributeValues. This way you can make normal developer/human calls.
https://github.com/rayepps/dynamof
db(update( table_name='users', key={ 'id': item['id'] }, attributes={ 'age': 26, 'name': 'Carl' }))disclaimer: I wrote it