Insert or update a user in database

Question

The code uses SQLAlchemy Core. However, what I want to know is if writing code in this pattern is recommendable.

def saveUser(self, user):
 """
 Inserts or updates a user in database.
 The method first checks if the provided user's id already exists. If no, then the user will be inserted. Otherwise, the stored values are updated.
 Args:
 user (User)
 Returns:
 User object with inserted id
 """
 result = self._engine.execute(self._userTable.select().where(self._userTable.c.Id == user._id))
 if not result.first():
 # user doesn't exist in database.
 result = self._engine.execute(self._userTable.insert(), Email=user.email, PasswordHash=user.passwordHash,
 DisplayName=user.displayName, Active=user.active)
 user._id = result.inserted_primary_key[0]
 else:
 # user already exists in database.
 result = self._engine.execute(self._userTable.update().where(self._userTable.c.Id == user._id),
 Email=user.email, PasswordHash=user.passwordHash, DisplayName=user.displayName, Active=user.active)
 return user
def deleteUser(self, userId=None, email=None):
 """
 Deletes a user.
 Either userId or email can be passed. If both are passed, then a user containing both userId and email will be deleted.
 If none of the arguments are provided, then the method call will have not effect.
 Args:
 userId (int): If this is None, only email will be used to delete the user.
 email (str): If this is None, only userId will be used to delete the user.
 """
 if not userId and not email:
 return # Because an empty and_ clause generated later on will raise OperationalError.
 idClause = self._userTable.c.Id == userId if userId else None
 emailClause = self._userTable.c.Email == email if email else None
 finalClause = and_(idClause, emailClause)
 deleteQuery = self._userTable.delete().where(finalClause)
 result = self._engine.execute(deleteQuery)

• Gareth Rees: You don't need to roll your own insert-or-update logic: SQLAlchemy has a merge method.
• Bhoot: @GarethRees - Isn't that limited to SQLAlchemy ORM? I am using Core here.

Answer 1

The only thing I can think of that might make it more Pythonic would be to wrap the body of deleteUser() in a try and catch and handle the OperationalError rather than checking user and email for None before making the attempt.