On Wednesday, October 28, 2015 at 10:30:13 AM UTC-4, Carlos Cesar Caballero
wrote:
>
> I can't do this:
>
> db.business.test = Field.Method(lambda row: 4)db.business.testa =
> Field.Virtual(lambda row: row.business.test())
> print db(db.business.id > 0).select().first().testa
>
>
> It's a bug?, a feature? or I am having a bad day?
>
> the exception is the clasic "<type 'exceptions.AttributeError'> 'Row'
> object has no attribute 'testa'"
>
> The same problem happened with two method fields or two virtual fields and
> I don't want to write the same code twice...
>
I observe the same problem, but I cannot reproduce it with two virtual
field or two method fields (or with a method field using a virtual field)
-- only in the exact case you have shown above.
Please submit a Github issue. In the meantime, to avoid redundancy, you can
do something like:
def test(row):
value = [some code]
return value
db.business.test = Field.Method('test', test)
db.business.testa = Field.Virtual('testa', lambda row: test(row))
Of course, in the above example, there is no reason to wrap test() in a
lambda in testa, but I assume the real lambda will include some additional
code along with the call to test().
Also, note that it is generally best to include a field name when creating
a Field.Method or Field.Virtual object, as otherwise the "name" attribute
of the virtual field will end up being "unknown", which will cause errors
in some contexts, such as SQLFORM.grid.
>
> An extra question:
>
why I need to do something like:
>
> lambda row: row.tablename.field
>
> something like this looks more elegant:
>
> lambda this: this.field
>
> just saying...
>
You can do:
lambda this: this.tablename.field
I'm not sure why we require the tablename -- maybe for consistency with the
old style virtual fields, which can be applied to joins and therefore need
to include the tablename as well as the field name.
Anthony
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