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Automatically exported from code.google.com/p/pymssql
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feature: more detailed exceptions #41

Open GoogleCodeExporter opened 9 years ago

GoogleCodeExporter commented 9 years ago 
When doing some debugging/testing, I noticed the following was output:

*** err_handler(dbproc = 0x22f28c0, severity = 9,  dberr = 20009, oserr = 111, 
dberrstr = 'Unable to connect: Adaptive Server is unavailable or does not 
exist',  oserrstr = 'Connection refused'); DBDEAD(dbproc) = 1
*** previous max severity = 0

This comes through to the Python developer as:

  File "_mssql.pyx", line 1349, in _mssql.maybe_raise_MSSQLDatabaseException (_mssql.c:12321)
    raise ex
MSSQLDatabaseException: (20009, 'Net-Lib error during Connection refused')

However, that message is pretty unhelpful to the python dev who doesn't 
understand the 20009 code/message is coming from TDS and/or doesn't know what 
to do with it.  

In order to make the messages less cryptic and more helpful, I would like to 
suggest making the string representation of a MSSQLException look something 
like:

DB: '<dberrstr>', OS: '<oserrstr>', tdscode: <dberr>, tdsmsg: '<dberr 
translation>'

So, the above exception would come through as:

MSSQLDatabaseException: DB: 'Unable to connect: Adaptive Server is unavailable 
or does not exist', OS: 'Connection refused', tdscode: 20009, tdsmsg: 'Net-Lib 
error during Connection refused'

Original issue reported on code.google.com by rsyr...@gmail.com on 12 Apr 2011 at 6:07

GoogleCodeExporter commented 9 years ago

Original comment by rsyr...@gmail.com on 8 Mar 2012 at 3:16

GoogleCodeExporter commented 9 years ago 
I took a stab at this that seems to work but needs more testing and review from 
some more eyes. This change adds more info to MSSQLDatabaseException:

http://code.google.com/r/msabramo-pymssql-issue41/source/detail?r=3d3d5934c2548d
24f83bdd9d01355ea585f11611

Sample usage:

vagrant@lucid64:~/dev/hg-repos/msabramo-pymssql-issue41$ .tox/py26/bin/python issue_41_mssql.py Traceback (most recent call last): File "issue_41_mssql.py", line 11, in charset='UTF-8') File "_mssql.pyx", line 1658, in _mssql.connect (_mssql.c:17029) return MSSQLConnection(_args, *_kwargs) File "_mssql.pyx", line 519, in _mssql.MSSQLConnection.init (_mssql.c:5007) maybe_raise_MSSQLDatabaseException(None) File "_mssql.pyx", line 1398, in _mssql.maybe_raise_MSSQLDatabaseException (_mssql.c:13506) raise ex _mssql.MSSQLDatabaseException: DB: 'Unable to connect: Adaptive Server is unavailable or does not exist', OS: 'Connection refused', tdscode: 20009, tdsmsg: 'Net-Lib error during Connection refused'


I didn't do anything with `pymssql.OperationalError` yet, which is what gets 
thrown if you use `pymssql.connect` rather than _mssql.connect.

Original comment by msabr...@gmail.com on 15 Jan 2013 at 3:51

GoogleCodeExporter commented 9 years ago 
If I do:

vagrant@lucid64:~/dev/hg-repos/msabramo-pymssql-issue41$ hg diff diff -r 3d3d5934c254 pymssql.pyx --- a/pymssql.pyx Tue Jan 15 07:47:20 2013 -0800 +++ b/pymssql.pyx Tue Jan 15 08:10:08 2013 -0800 @@ -553,7 +553,7 @@ appname, port)

 except _mssql.MSSQLDatabaseException, e:

then I get a nicer exception when `pymssql.connect` fails:

vagrant@lucid64:~/dev/hg-repos/msabramo-pymssql-issue41$ .tox/py26/bin/python issue_41.py Traceback (most recent call last): File "issue_41.py", line 12, in charset='UTF-8') File "pymssql.pyx", line 556, in pymssql.connect (pymssql.c:7990) raise OperationalError(e) pymssql.OperationalError: DB: 'Unable to connect: Adaptive Server is unavailable or does not exist', OS: 'Connection refused', tdscode: 20009, tdsmsg: 'Net-Lib error during Connection refused'


but I don't understand what `e[0]` was doing, so not sure if it's OK to change 
it. If it is OK, then there are a bunch of places in `pymssql.pyx` that catch 
MSSQLDatabaseException and raise an OperationalError and perhaps these should 
be changed as well, but these are lot of hard-to-reproduce edge cases, so I'm 
not sure how to proceed.

Original comment by msabr...@gmail.com on 15 Jan 2013 at 4:17

GoogleCodeExporter commented 9 years ago

Original comment by msabr...@gmail.com on 7 Aug 2013 at 1:56

GoogleCodeExporter commented 9 years ago 
> Traceback (most recent call last):
  File "issue_41.py", line 12, in <module>
    charset='UTF-8')
  File "pymssql.pyx", line 556, in pymssql.connect (pymssql.c:7990)
    raise OperationalError(e)
pymssql.OperationalError: DB: 'Unable to connect: Adaptive Server is 
unavailable or does not exist', OS: 'Connection refused', tdscode: 20009, 
tdsmsg: 'Net-Lib error during Connection refused'

but I don't understand what e[0] was doing, so not sure if it's OK to change it.

From PEP 3110 and PEP 352 an exception instance could (before Python 3) be accessed by index. The values obtained were the ones passes when instantiaging/raising it (if any), in the same order.

So when pymssql.pyx catches MSSQLDatabaseException as e and the treats it raising a pymssql-level exception with value e[0] it's actually passing to the user the two-element tuple with which maybe_raise_MSSQLDatabaseException() is instantiating it:

MSSQLDatabaseException((get_last_msg_no(conn), get_last_msg_str(conn)))

The tuple is the one we are uded to see when dealing with pymssql/[Feee]TDS:

(20009, 'Net-Lib error during Connection refused')

Something similar (but simpler) happens when it catches MSSQLDriverException as e, raising a new exception with value e[0] simply makes the string reported by _mssql.pyx bubble up to the user.


Original comment by `cra...@gmail.com` on 16 Aug 2013 at 10:37
GoogleCodeExporter commented 9 years ago

Original comment by msabr...@gmail.com on 23 Sep 2013 at 10:06

GoogleCodeExporter commented 9 years ago

Original comment by msabr...@gmail.com on 23 Sep 2013 at 10:15