You are right. Not sure why this happens but I will look into it. Could you
please open a ticket so this is tracked?
On Wednesday, 7 August 2013 04:24:50 UTC-5, Andrew Buchan wrote:
>
> Massimo,
> I tried opening a base url from IE when it had crashed in a session in
> Chrome and got no response, so assume it is indeed web2py that crashed.
> This was with a field which says ondelete='NO ACTION'. Can we not infer
> from the fact pyodbc raised an Exception that was caught by web2py that
> control did indeed return to web2py, or is that not correct?
>
> Some info:
>
> web2py™ Version 2.5.1-stable+timestamp.2013.06.06.15.39.19
>
> Traceback (most recent call last):
> File "/home/mdipierro/make_web2py/web2py/gluon/restricted.py", line 212,
> in restricted
> File
> "N:/IT/Dev/Code/HubForms/web2py/applications/HubForms/models/7_models_boots_database.py",
>
> line 104, in <module>
> File "/home/mdipierro/make_web2py/web2py/gluon/dal.py", line 7788, in
> define_table
> File "/home/mdipierro/make_web2py/web2py/gluon/dal.py", line 7825, in
> lazy_define_table
> File "/home/mdipierro/make_web2py/web2py/gluon/dal.py", line 991, in
> create_table
> File "/home/mdipierro/make_web2py/web2py/gluon/dal.py", line 1094, in
> migrate_table
> File "/home/mdipierro/make_web2py/web2py/gluon/dal.py", line 1784, in
> execute
> File "/home/mdipierro/make_web2py/web2py/gluon/dal.py", line 1778, in
> log_execute
> ProgrammingError: ('42000', "[42000] [Microsoft][ODBC SQL Server
> Driver][SQL Server]The object 'boots_project_rfi_testing__constraint' is
> dependent on column 'testing'. (5074) (SQLExecDirectW); [42000]
> [Microsoft][ODBC SQL Server Driver][SQL Server]ALTER TABLE DROP COLUMN
> testing failed because one or more objects access this column. (4922)")
>
>
>
> On Wed, Aug 7, 2013 at 9:29 AM, Massimo Di Pierro
> <[email protected]<javascript:>
> > wrote:
>
>> Could this be a pyodbc issue? Are you sure web2py hangs or only this one
>> session hangs? You can try from two separate browsers. It is possible
>> pyodbc does not return (because for example a circular reference is on
>> delete cascade) and web2py keeps the session blocked. All requests from
>> this user/session are queued.
>>
>>
>> On Tuesday, 6 August 2013 20:02:51 UTC-5, Andrew Buchan wrote:
>>>
>>> We have the same (similar) issue using mssql on Windows: when we get a
>>> pyodbc.ProgrammingError typically relating to a foreign key, we have to
>>> restart web2py.
>>>
>>> This is particularly frustrating problem as these errors happen every
>>> time you rename/delete a column with a foreign key.
>>>
>>> E.g. create a field that references another table:
>>> .....
>>> Field('a_field', db.another_table, ondelete='CASCADE'),
>>> ....
>>> Then remove/rename ;a_field', and you get "ALTER TABLE DROP COLUMN
>>> a_field failed because one or more objects access this column."
>>>
>>> This causes web2py to hang, so we have to go into management studio,
>>> delete the constraint, and restart web2py because it has become
>>> unresponsive.
>>>
>>> I think that, aside from resolving why web2py hangs, we could also
>>> improve migration so that it deletes any constraints automatically when we
>>> drop a column.
>>>
>>> While we're at it, web2py could check a column actually exists before
>>> calling a DROP statement. It frequently happens that things do get out of
>>> synch with fake migrates and manually modifying the table etc, and for a
>>> DROP statement to be called on a column that has been removed. There is
>>> really no benefit in web2py failing if the column to delete isn't found.
>>>
>>> I thought I'd reply to this thread (ps: right thing to do?) and see if
>>> anyone had any suggestions/info before I go raising as bugs/features, or
>>> attempting to produce a patch...
>>>
>>>
>>>
>>> --
>>
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