Raise a psycopg error with a specific pgcode

[arjenzorgdoc]

For some tests I tried to raise a psycopg2 error with a specific pgcode.

How do I do that?

[dvarrazzo]

Maybe using psycopg2.errors.lookup()

[arjenzorgdoc]

Oh sorry for my bad description. I know which error to raise. But I cannot set the pgcode.

raise SerializationFailure('40001', '40001', '40001')

raise SerializationFailure(pgcode='40001')

e = SerializationFailure()
e.pgcode = '40001'
raise e

None of these seem to work.

[arjenzorgdoc]

>>> t = psycopg2.errors.lookup('40001')
>>> t
<class 'psycopg2.errors.SerializationFailure'>
>>> t()
SerializationFailure()
>>> print(_.pgcode)
None

[dvarrazzo]

Then maybe it's not possible because in psycopg2 database errors are only expected to be raised from C and the attribute is read-only from Python.

In psycopg 3 what you want to do is not a problem:

>>> try: raise psycopg.errors.lookup("40001")()
... except Exception as ex: e = ex

>>> e.sqlstate
'40001'