I have noticed that if i make a odoo json rpc call, im doing it with postman, to a function called my_function that does the following

def my_function(self, values):
mess = "Success"
try:
holder = self.prepare_values(values)
#This perform an operations that sometimes result in an exception, because the sended values are wrong
#for example, if the function first create record in a model example.example, and then raises an exception
#the created record still remains after throwing the exception and returning the answer
self.do_something(holder)
except Exception as err:
mess = "Something went wrong"

return mess

Is this the normal behavior? In my experience even if I catch the exception the changes made by the function that throw the exception should not remain. If this is the normal behavior, what can I do to revert or prevent saving the changes made by the function that gave exception?