Thank you, that clarifies things for me.
On Thursday, 30 July 2015 11:09:07 UTC-4, Anthony wrote:
>
> Same answer. Each request is handled in a separate thread, so any code in
> a model, controller, or view is run in a fresh environment. When you define
> a table or specify callbacks in a model file, it's like it is happening for
> the first time (as it only applies to the current request) -- it is not as
> if a new copy of your callback function is being appended to an
> ever-growing list on every request. You would only be appending the same
> function twice if your code includes:
>
> db.tt._after_update.append(myfunc)
>
> in two separate places.
>
> Anthony
>
> On Thursday, July 30, 2015 at 11:01:51 AM UTC-4, Thomas Sitter wrote:
>>
>> Sorry I should have clarified my question.
>>
>> The part I'm concerned about is the use of *append* when adding the
>> callback. If append is being used is there any check to make sure a
>> function is not already in the list. I do not want to call the same
>> callback multiple times when a record is updated.
>>
>> In the sourcecode _after_callback is implemented as a list and I see no
>> checks to make sure the same function isn't inserted/called more than once.
>> Perhaps it should be a set?
>>
>>
>>
>> On Thursday, 30 July 2015 00:50:49 UTC-4, Anthony wrote:
>>>
>>> auth.add_group() actually does a database insert, so you don't want to
>>> keep repeating it on every request (actually, I would probably move that
>>> code out of the app altogether, as it really only needs to be run once
>>> ever).
>>>
>>> Specifying the after update callback, on the other hand, does not affect
>>> the database at all -- it simply tells the DAL what to do after a database
>>> update. In fact, you need this to run on every request because it is part
>>> of the model definition (for the same reason you need to run the associated
>>> db.define_table() on every request).
>>>
>>> Anthony
>>>
>>> On Wednesday, July 29, 2015 at 10:59:59 PM UTC-4, Thomas Sitter wrote:
>>>>
>>>> Hello,
>>>>
>>>> I'm adding an _after_update callback to my table in db.py using:
>>>>
>>>> def myfunc(s,f):
>>>> #do stuff
>>>> return False
>>>>
>>>> db.tt._after_update.append(myfunc)
>>>>
>>>> My question is whether this will continuously append this method every
>>>> time a database table is modified.
>>>>
>>>> I'm asking because I had a similar issue when creating the initial auth
>>>> users/groups in db.py. I had to wrap the code in the following logic to
>>>> prevent them being added multiple times
>>>>
>>>> if not db().select(db.auth_user.ALL).first():
>>>> group_1 = auth.add_group('group1', 'group1 employees')
>>>> ...
>>>>
>>>>
>>>> Thanks
>>>>
>>>
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