uhm. please take into consideration that you can't hook to the
"after_delete" callback if you still want to access the record that has
been deleted...... use before_delete for that case.
Il giorno giovedì 9 maggio 2013 01:40:49 UTC+2, Jurgis Pralgauskis ha
scritto:
>
> Thanks,
>
> hm, ok, my usecase is more problematic,
>
>
> db.define_table('Product',
> Field('name',),
> Field('price', 'decimal(10,2)'),
> Field('quantity', 'integer'),
> Field('*quantity_sold*', 'integer'), # this could be virtual - but
> then it does not play with queries...
> )
>
> I want to refresh *quantity_sold* after each Purchase
> (insert/update/delete)
> but after delete I'd like to still access which product it has been?
> if I do it before delete, the purchace is still there - and my aggregate
> function sums it (though I need it gone) ...
>
> db.define_table('Purchase',
> Field('product', db.Product),
> Field('quantity', 'integer'),
> )
>
> def update_Product_quantity_from_Purchase( purchase ):
> q_sum = db.Purchase.quantity.sum()
> quantity_sold =
> db(db.Purchase.product== purchase.product ).select(q_sum).first()[q_sum] or
> 0
> db.Product[purchase.product].update_record( *quantity_sold*
> =quantity_sold )
>
>
> db.Pardavimai._after_insert.append( lambda
> f,id: update_Product_quantity_from_Purchase(f) )
> db.Pardavimai._after_update.append( lambda
> s,f: update_Product_quantity_from_Purchase(s.select()[0]) )
> db.Pardavimai._after_delete.append( lambda
> s: update_Product_quantity_from_Purchase(s.select()[0]) ) #ERR
>
> ***
> Ha, while writing I came up with workaround - _before_delete
> I add extra parameter to my update_Product... function, which tells that
> purchase stuff should be subtracted in advance (as it will be detelted)
>
> def update_Product_quantity_from_Purchase( purchase, deleting=False ):
> ...
> if deleting:
> quantity_sold -= purchace.quantity
> db.Product[purchase.product].update_record( *quantity_sold*=quantity_sold
> )
>
> db.Pardavimai._before_delete.append( lambda
> s: update_Product_quantity_from_Purchase(s.select()[0], True) ) #OK
>
> ***
> ps.: Maybe similar functionality could be extended for "compute'd" field?
> If it knew what foreign tables&fields it depends on, the
> triggers/callbacks could be added automatically?
>
>
>
>
> On Thu, May 9, 2013 at 2:06 AM, Anthony <[email protected]
> <javascript:>>wrote:
>
>> If the query only has that one condition, then you can do:
>>
>> s.query.second
>>
>> A Set object has a "query" attribute, which is a Query object, and a
>> Query object has "op", "first", and "second" attributes. So, s.query gets
>> the Query object of the Set, and s.query.second gets the second operand of
>> the "==" operator. If instead you have multiple conditions in the query,
>> keep in mind that the operands of the "&" operator are themselves Query
>> objects. So, if you have:
>>
>> set = db((db.person.id > 10) & (db.person.name.startswith('A')))
>>
>> you can extract the 10 from the first part of the query via:
>>
>> set.query.first.second
>>
>> In that case, set.query.first itself returns a Query (i.e., db.person.id>
>> 10), so set.query.first.second gives you the 10.
>>
>> Keep in mind that these properties of Set and Query are internal and not
>> part of the API, so this isn't guaranteed to remain backward compatible.
>>
>> Another option is to pass the Set to the str() function, which generates
>> a string that contains the SQL produced by the query. You could then do
>> some parsing of that string to get what you want. For example, in this case
>> you get:
>>
>> >>> str(db(db.person.id == 1))
>> '<Set (person.id = 1)>'
>>
>> You can use a regex to get the 1 from that string.
>>
>> Anthony
>>
>>
>> On Wednesday, May 8, 2013 6:10:05 PM UTC-4, Jurgis Pralgauskis wrote:
>>>
>>> Hi,
>>>
>>> I look at example:
>>> http://www.web2py.com/book/**default/chapter/06#before-and-**
>>> after-callbacks<http://www.web2py.com/book/default/chapter/06#before-and-after-callbacks>
>>>
>>> how can I find out what is the value of person.id from the set without
>>> select?
>>> (<Set (person.id = 1)>,)
>>>
>>> as I tried:
>>> s.select(..)[0] # it worked for update
>>> but got
>>>
>>> Traceback (most recent call last):
>>> File "/home/nijole/Downloads/**EasyVet/web2py/gluon/**restricted.py",
>>> line 212, in restricted
>>>
>>> exec ccode in environment
>>> File
>>> "/home/nijole/Downloads/**EasyVet/web2py/applications/**apskaitele/controllers/**appadmin.py"
>>>
>>> <http://localhost:8000/admin/default/edit/apskaitele/controllers/appadmin.py>,
>>> line 569, in <module>
>>>
>>> File "/home/nijole/Downloads/**EasyVet/web2py/gluon/globals.**py", line
>>> 194, in <lambda>
>>>
>>> self._caller = lambda f: f()
>>>
>>> File
>>> "/home/nijole/Downloads/**EasyVet/web2py/applications/**apskaitele/controllers/**appadmin.py"
>>>
>>> <http://localhost:8000/admin/default/edit/apskaitele/controllers/appadmin.py>,
>>> line 304, in update
>>>
>>> if form.accepts(request.vars, session):
>>>
>>> File "/home/nijole/Downloads/**EasyVet/web2py/gluon/sqlhtml.**py", line
>>> 1398, in accepts
>>>
>>> self.table._db(qry).delete()
>>>
>>> File "/home/nijole/Downloads/**EasyVet/web2py/gluon/dal.py", line 9821,
>>> in delete
>>>
>>> ret and [f(self) for f in table._after_delete]
>>>
>>> File
>>> "/home/nijole/Downloads/**EasyVet/web2py/applications/**apskaitele/models/db.py"
>>> <http://localhost:8000/admin/default/edit/apskaitele/models/db.py>, line
>>> 329, in <lambda>
>>>
>>> db.Pardavimai._after_delete.ap**pend( lambda s:
>>> update_SandelioProduktai_**likutis_from_Pardavimai(s.sele**ct(db.Pardavimai.sandelio_**produktas)[0])
>>> )
>>>
>>> File "/home/nijole/Downloads/**EasyVet/web2py/gluon/dal.py", line 10075,
>>> in __getitem__
>>>
>>> row = self.records[i]
>>> IndexError: list index out of range
>>>
>>>
>>>
>>> --
>>
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>>
>>
>
>
>
> --
> Jurgis Pralgauskis
> tel: 8-616 77613;
> Don't worry, be happy and make things better ;)
> http://galvosukykla.lt
>
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