Oops, of course, the select is done within setdefault. Your if statement
version is the way to go.
Anthony
On Thursday, August 15, 2013 3:21:43 PM UTC-4, Quint wrote:
>
> Thanks!
>
> Got it woking now but i got strange results:
>
> ("Not working" means that the same referenced record is being fetched
> every time and not read from the dict)
>
> This is not working:
>
> Field.Virtual('created_by_record',
> lambda r: users.setdefault(r.comment.created_by.id, db
> .auth_user(r.comment.created_by))),
>
> This is also not working:
>
> users = {}
> def created_by_record(r):
> k = r.comment.created_by.id
> return users.setdefault(k, db.auth_user(k))
>
>
> Field.Virtual('created_by_record', created_by_record),
>
> But this is working:
>
> users = {}
> def created_by_record(r):
> k = r.comment.created_by.id
> if k in users:
> return users[k]
> users[k] = db.auth_user(k)
> return users[k]
>
>
> Field.Virtual('created_by_record', created_by_record),
>
>
>
>
>
>
> On Thursday, August 15, 2013 6:37:18 PM UTC+2, Anthony wrote:
>>
>> Good point. I suppose you can adapt your method to work with a virtual
>> field:
>>
>> owners = {}
>> db.define_table('dog',
>> ...
>> Field.Virtual('owner_record',
>> lambda r: owners.setdefault(r.dog.owner, db.person(r.dog.owner)))
>>
>> That will store each fetched owner record in the owners dict, so the
>> record will be copied from the dict if it is already there rather than
>> pulled from the db.
>>
>> Anthony
>>
>> On Thursday, August 15, 2013 12:09:02 PM UTC-4, Quint wrote:
>>>
>>> But when when a row is calculating it's virtual field, it will fetch the
>>> referenced row even when some other row from the initial set has already
>>> fetched this same referenced row (when they are referencing the same
>>> thing). So they will both perform the same fetch.
>>>
>>> ?
>>>
>>> I want to do this fetch 1x and use that record for all rows from the
>>> initial set that reference it.
>>> On Aug 15, 2013 4:18 PM, "Anthony" <abas...@gmail.com> wrote:
>>>
>>>> On Thursday, August 15, 2013 10:04:45 AM UTC-4, Quint wrote:
>>>>
>>>>> thnx,
>>>>>
>>>>> but my goal is to prevent repeated queries for the same record when
>>>>> accessing ref fields on rows from the same result set.
>>>>>
>>>>> I'm missing something, how do those Virtual Fields achieve that?
>>>>>
>>>>
>>>> Yes, that's exactly what the virtual field does -- when the the Rows
>>>> object is created from the initial select, the value of the virtual field
>>>> is calculated for each Row, and it remains in the Row (i.e., it is not
>>>> re-calculated on each access). There is also Field.Method(), which does
>>>> re-calculate on every access (the advantage is that it is lazy, so nothing
>>>> is calculated until accessed -- and because of that, it can take arguments
>>>> at the time it is called).
>>>>
>>>> And about the join, wouldn't that mean it won't work on GAE?
>>>>>
>>>>
>>>> Oh, yeah, forgot you said you are on GAE.
>>>>
>>>> Anthony
>>>>
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>>>>
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