id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
16948	Django DB backends hid information in database exceptions	James Henstridge	nobody	"The Django DB backends replace the exceptions raised by the underlying adapter with standard ones from django.db.utils.

I understand the reason for doing this (provide standard exceptions that calling code can catch), but it can lose information provided by those exceptions.  For example, the psycopg2 adapter exposes the SQL error code as a ""code"" attribute on exceptions, and this is lost.

Perhaps using the same strategy as Storm would help: rather than catching the adapter's exceptions and re-raising equivalent standard ones, it patches the adapter's exceptions so that they subclass from the standard ones.  This could be done with a method like the following:

    {{{
def install_exceptions(module):
    if not isinstance(module.DatabaseError, django.db.utils.DatabaseError):
        module.DatabaseError.__bases__ += (django.db.utils.DatabaseError,)
    if not isinstance(module.IntegrityError, django.db.utils.IntegrityError):
        module.IntegrityError.__bases__ += (django.db.utils.IntegrityError,)
}}}

Once the adapter's exceptions have been patched it would no longer be necessary to wrap the adapter's cursors, since the standard cursor would raise exceptions that could be caught by generic code."	Uncategorized	closed	Database layer (models, ORM)	dev	Normal	duplicate		James Henstridge	Unreviewed	1	0	0	0	0	0