Thanks Anthony ... I'm sorry say but can not remember for what i needed that code snippet .... thanks any way.. is good to know that stuff.
2016-09-16 17:02 GMT-04:00 Anthony <[email protected]>: > This is a quirk of Field objects. Field inherits from Expression, and the > __eq__ method of Expression returns a Query object (rather than testing for > equality and returning a boolean). So, if you do something like myfield == > some_object, you do not actually get a test of whether myfield is equivalent > to some_object. Instead, you just get a Query object, which apparently > evaluates to True in the code Python uses to check for the existence of an > element in a list. It works this way so you can create DAL queries using the > db.mytable.myfield == some_value syntax. > > If you want to check for a field in a list, consider instead storing the > field names: > > f = db.item.id > fields = [f.name] > f.name in fields > > Or using your current code, you can do: > > any(field is f for field in fields) > > Above, field == f would result in the same problem, but field is f avoids > the creation of the Query object. > > Anthony > > > On Friday, September 16, 2016 at 12:41:28 PM UTC-4, Yoel Benitez Fonseca > wrote: >> >> Does this make sense to you? >> >> In [1]: fields = list() >> >> In [2]: f = db.item.id >> >> In [3]: f in fields >> Out[3]: False >> >> In [4]: fields.append(f) >> >> In [5]: f in fields >> Out[5]: True >> >> In [6]: f = db.item.headline >> >> In [7]: f in fields >> Out[7]: True >> >> I mean, the last value of 'f' is a fields object but a different one. >> >> -- >> Yoel Benítez Fonseca >> http://redevil.cubava.cu/ >> $ python -c "import this" > > -- > 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) > --- > You received this message because you are subscribed to the Google Groups > "web2py-users" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > For more options, visit https://groups.google.com/d/optout. -- Yoel Benítez Fonseca http://redevil.cubava.cu/ $ python -c "import this" -- 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) --- You received this message because you are subscribed to the Google Groups "web2py-users" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
