getlist question

[Carsten Haese]

Victor Subervi wrote:
> On Fri, Dec 25, 2009 at 11:35 AM, Carsten Haese <carsten.haese at gmail.com
> <mailto:carsten.haese at gmail.com>> wrote:
> 
>     Victor Subervi wrote:
>     > Well I've done that. What happens is the storeColNames registers the
>     > "Availability" field naturally enough; however, as I stated
>     before, the
>     > getlist doesn't fetch anything because there is nothing to fetch! No
>     > such value is passed!
> 
>     Well, what does getlist return when the situation you're describing as
>     "getlist doesn't fetch anything" occurs? Does is raise an exception?
>     Does it return 0? Does it return None? Does it return an empty list? An
>     empty string? An empty tuple? Does it return False? Does it not return
>     at all and causes the universe to fall into a black hole?
> 
> 
> It returns nothing. I believe I've stated that three times now.

Bzzzt! Wrong! "Nothing" is not a Python object, and stating it three
times doesn't make it any less wrong. The result you're getting is a
Python object. It might represent Nothingness to you, but it's not
nothing. Try to find out what that object is, so that you can then use a
Python if-statement to check whether the return value you're getting is
such an object.

> 
>      So, what I need to do is figure out a way to log
>     > the fact that no value is fetched. What I have currently,
>     unfortunately,
>     > simply ignores the unfetchable value. As I stated before, I need
>     to log
>     > the fact that no such value is obtained. Please...how do I do that??
> 
>     Please be less vague. What part do you have a problem with? Checking
>     whether "no value is fetched" or "log the fact"?
> 
> 
> No value is fetched because there is no value to fetch. I want to be
> able to log the fact that no value was fetched. How do I do that? Am I
> not being clear? Here, let me try again, as I began this thread with my
> first post. I thought it was so easy, so clear. If I use getfirst, I can
> set a default to log whether getfirst gets anything or not. I cannot do
> that with getlist. Is there a work-around?

See above. Try to find out what kind of object it does return in the
case that's causing you grief, and then devise a Python if-statement to
test for that object. Hint: Use type() and repr() to find out what
getlist() is returning.

--
Carsten Haese
http://informixdb.sourceforge.net