According to the Python DB API specification, there should be a common set
of exceptions <https://www.python.org/dev/peps/pep-0249/#exceptions>, and
they should be exposed as attributes on the connection object
<https://www.python.org/dev/peps/pep-0249/#connection-error>. Therefore,
you should be able to do something like:
try:
db.mytable.insert(**fields)
except (db._adapter.driver.IntegrityError, db._adapter.driver.
OperationalError) as e:
pass
The above should catch the IntegrityError and OperationalError of any DB
API compliant driver.
Also, when making inserts or updates, if you don't care about the specific
exception but just want to catch any database errors, the DAL API includes
the following:
db.mytable._on_insert_error = my_insert_error_handler
db.mytable._on_update_error = my_update_error_handler
Anthony
On Wednesday, September 7, 2016 at 1:14:54 PM UTC-4, Joe Barnhart wrote:
>
> So my website runs under PostgresSQL today but will likely be switched to
> MySql at some point in the future. My problem isn't with the DAL -- it
> performs fine for what it does, insulating me very well from the nuances of
> the SQL syntax for each engine.
>
> No, my problem comes from Exceptions. Each database engine defines its
> own Exceptions within its driver. Even different drivers for the same
> database engine (psycopg2 vs pg8000) come with different Exception trees.
> If I want to be able to handle database exceptions (and who doesn't?) how
> do I load and use the RIGHT set of Exceptions for each driver?
>
> When using the pg8000 driver for example, the Exceptions raised are all of
> the form: "gluon.contrib.pg8000.ProgrammingError" or some such. Errors
> from psycopg2 and the mysql drivers are similarly formed. I can't even use
> this in a try-except block unless I first import gluon.contrib.pg8000. The
> same is true for exceptions from all other database engines.
>
> Should we "alias" these database errors into a consistent tree inside
> web2py? If we created a database exception tree inside web2py, and then
> added to the database driver module a section that raised the corresponding
> web2py Exception whenever a database exception was triggered, then we could
> just catch ProgrammingError (from web2py) instead of
> gluon.contrib.pg8000.ProgrammingError.
>
> Or, should I just put somewhere in the db definition of the models a line
> like "import gluon.contrib.pg8000 as mydb" and then use
> "mydb.ProgrammingError" throughout my code? I suppose I'd need to repeat
> this in every module I create, and I create a LOT of modules....
>
> Anyway, is this a real problem or am I missing something obvious??
>
> -- Joe
>
>
--
Resources:
- http://web2py.com
- http://web2py.com/book (Documentation)
- http://github.com/web2py/web2py (Source code)
- https://code.google.com/p/web2py/issues/list (Report Issues)
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