Greetings,
I just started using py4web, and I'm very excited to do so.
Has there been any more thought on this issue? I was partially into a new
web2py app in which I use _enable_record_versioning(), and I am migrating
it to py4web.
Thanks.
On Saturday, August 17, 2019 at 10:34:21 PM UTC-7, Massimo Di Pierro wrote:
>
> Sorry for the late response. I just run into this myself. Do not have a
> good solution at this time, unless we make pydal aware of
> ThreadSafeVariable(s). Maybe we have to.
>
> On Wednesday, 31 July 2019 05:05:50 UTC-7, Manuel Vio wrote:
>>
>> Ok, I narrowed the problem a bit:
>>
>> In py4web/core.py, around line 207, there is this adjustment in order to
>> make some variables threadsafe:
>>
>> # make sure some variables in pydal are thread safe
>> for _ in ['readable', 'writable', 'default', 'update', 'requires']:
>> setattr(pydal.DAL.Field, _, threadsafevariable.ThreadSafeVariable())
>>
>> Turns out that PyDAL's _enable_record_versioning(), in order to create
>> the archive table, clones all original fields with their properties. Or, at
>> least, it tries to: it seems that copy() fails to correctly transfer
>> threadsafevariable informations when dealing with those variables.
>> I guess that when cloned field's requires attribute is accessed those
>> information are not valid anymore and py4web throws the aforementioned
>> exception.
>> I was able to circumvent this error adding an explicit copy of the
>> attribute in pydal, but still I'm not sure if this could eventually lead to
>> thread problems:
>>
>> for field in self:
>> nfk = same_db or not field.type.startswith('reference')
>> clone = field.clone(unique=False, type=field.type if nfk else 'bigint')
>> clone.requires = copy.copy(field.requires)
>> clones.append(
>> clone
>> )
>>
>>
>> Any thougths?
>>
>
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