I've been trying to debug this but the learning curve is steep. If you
generate a query like so:
db.person.full_name = Field.Virtual('full_name',lambda row: 999)
qry = db.person
set = db(qry)
res = set.select()
then the virtual field is not included in the SQL sent to the database.
parse in dal.py adds it after the database query.
The grid code adds the field to the list of columns and fields, which means
it ends up in the SQL sent to the database, results in a database error
(since the field is not really in the table)
I'm not sure if there is a post-query scan for virtual fields in the grid,
at least I couldn't find it.
On Saturday, 28 September 2013 04:40:49 UTC+10, hiro wrote:
>
> Thank you!
>
> On Friday, September 27, 2013 8:14:55 PM UTC+2, Massimo Di Pierro wrote:
>>
>> I can confirm the problem and I opened a ticket:
>>
>> https://code.google.com/p/web2py/issues/detail?id=1692
>>
>> On Thursday, 19 September 2013 03:49:35 UTC-5, hiro wrote:
>>>
>>> In the book I read:
>>>
>>> *Showing virtual fields in SQLFORM.grid and smartgrid*
>>> In recent versions of web2py, virtual fields are shown in grids like
>>> normal fields: either shown alongside all other fields by default, or by
>>> including them in the fields argument. However, virtual fields are not
>>> sortable.
>>>
>>> However, if i use the welcome app and define:
>>>
>>> db.define_table('entity',
>>> Field('entity_name', 'string'),
>>> Field('slogan', 'string'),
>>> Field.Virtual('slogan2', lambda row: row.entity.slogan+', it is
>>> really the best.')
>>> )
>>>
>>> and then create a grid:
>>>
>>> def index():
>>> my_grid = SQLFORM.grid(db.entity)
>>> return locals()
>>>
>>> Reading the book I expect this to work. However I get the error 'Query
>>> Not Supported: no such column: entity.slogan2' in the smartgrid.
>>>
>>> Massimo, is this related to to the same bug I asked about yesterday? (I
>>> have not yet updated my web2py to trunk, but did not find anything about
>>> this issue in the tracker.)
>>>
>>> One solution might be to change the Virtual Fiels to computed fields.
>>>
>>> A big hug to all web2py contributors!
>>>
>>> Edit: Using stable version of 2.6.4
>>>
>>
--
Resources:
- http://web2py.com
- http://web2py.com/book (Documentation)
- http://github.com/web2py/web2py (Source code)
- https://code.google.com/p/web2py/issues/list (Report Issues)
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