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I have a view in flask that I want to use to display success when an object from a POST request is successfully committed.
In the controller, I have
us = User(data_that_is_not_valid)
db_session.add(us)
db_session.commit()
As of now, db_commit() throws an exception when the object can't be committed. Is there a more friendly way that just returns true or false to specify whether the object has been added to the database without throwing an error?
EDIT: Added copy of exception
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/usr/local/lib/python2.7/dist-packages/SQLAlchemy-0.8.0-py2.7-linux-x86_64.egg/sqlalchemy/orm/scoping.py", line 149, in do
return getattr(self.registry(), name)(*args, **kwargs)
File "/usr/local/lib/python2.7/dist-packages/SQLAlchemy-0.8.0-py2.7-linux-x86_64.egg/sqlalchemy/orm/session.py", line 719, in commit
self.transaction.commit()
File "/usr/local/lib/python2.7/dist-packages/SQLAlchemy-0.8.0-py2.7-linux-x86_64.egg/sqlalchemy/orm/session.py", line 350, in commit
self._assert_active(prepared_ok=True)
File "/usr/local/lib/python2.7/dist-packages/SQLAlchemy-0.8.0-py2.7-linux-x86_64.egg/sqlalchemy/orm/session.py", line 192, in _assert_active
% self._rollback_exception
sqlalchemy.exc.InvalidRequestError: This Session's transaction has been rolled back due to a previous exception during flush. To begin a new transaction with this Session, first issue Session.rollback(). Original exception was: (IntegrityError) column email is not unique u'INSERT INTO users (name, email, password) VALUES (?, ?, ?)' ('test', '[email protected]', 'test')
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commit() will then COMMIT the actual database transaction or transactions, if any, that are in place. Finally, all objects within the Session are expired as the transaction is closed out.
Nested Transaction begin_nested() methods, the transaction object returned must be used to commit or rollback the SAVEPOINT. Calling the Session. commit() or Connection. commit() methods will always commit the outermost transaction; this is a SQLAlchemy 2.0 specific behavior that is reversed from the 1.
The flush process always occurs within a transaction, even if the Session has been configured with autocommit=True , a setting that disables the session's persistent transactional state. If no transaction is present, Session. flush() creates its own transaction and commits it.
_sa_instance_state is a non-database-persisted value used by SQLAlchemy internally (it refers to the InstanceState for the instance. While not directly relevant to this section, if we want to get at it, we should use the inspect() function to access it).
Your data should be prepared anyway. But this case is not data format case
And exception is always good, you just need to catch and use them
You should consider exception as returned False, also you should log the reason for fail for later solving of problem
failed=False
try:
db_session.commit()
except Exception as e:
#log your exception in the way you want -> log to file, log as error with default logging, send by email. It's upon you
db_session.rollback()
db_session.flush() # for resetting non-commited .add()
failed=True
#some use of failed var, specific for your case if you need it
For better understanding of exceptions: Exceptions python docs
As for your specific exception looks like autocommit is your issue. Or not commited some previous SQL operation: Sqlalchemy docs
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