Re: [sparql-wrapper-devel] Empty result items from SPARQLWrapper return empty list instead of object with attribute items that conains empty list

[Sergio F. <se...@wi...>]

Hi again,

today I'm quite busy, so I can't go deeper into SuRF's source code.
Could you please provide me details about the trace how resource_d is
build at [1]? Because you're directly using
results["results"]["bindings"], that's a list, so it's wrong (this
code will not work [2], for instance) and will produce the reported
exception even with results. It should access a concrete binding of
the results (as this code does [3]).

Awaiting for your support on that.

Cheers,


[1] http://code.google.com/p/surfrdf/source/browse/trunk/surf/resource/__init__.py#548
[2] http://gist.github.com/3705188
[3] http://gist.github.com/3705219

On 12 September 2012 09:53, Sergio Fernández <se...@wi...> wrote:
> Hi Laurens,
>
> when SuRF performs:
>
>> "c:\python27-32\lib\site-packages\surf-1.1.6r0_r374-py2.7.egg\surf\resource\__init__.py"
>> in __set_predicate_values
>>   571.         for p, v in results.items():
>
> it's because to get a dictionary there, but a list was returned. I'll
> investigate why such container is returned when the result set comes
> empty, because that's something that should be handle by the library.
>
> I'll keep you informed.
>
> Kind regards,
>
>
> On 11 September 2012 11:15, Laurens De Vocht <lau...@gm...> wrote:
>>
>> Hi,
>>
>>
>> When I switched from the Allegrograph SurfRDF to SPARQLWrapper SurfRDF, I
>> suddenly get this error (both with Virtuoso and Fuseki SPARQL Endpoints):
>>
>> Environment:
>>
>>
>> Request Method: GET
>> Request URL: http://localhost:8000/leden/done/
>>
>> Django Version: 1.4.1
>> Python Version: 2.7.3
>> Installed Applications:
>> ('django.contrib.auth',
>>  'django.contrib.contenttypes',
>>  'django.contrib.sessions',
>>  'django.contrib.sites',
>>  'django.contrib.messages',
>>  'django.contrib.staticfiles',
>>  'social_auth',
>>  'twitter',
>>  'surf',
>>  'hamlpy',
>>  'djaml',
>>  'django.contrib.admin',
>>  'leden')
>> Installed Middleware:
>> ('django.middleware.common.CommonMiddleware',
>>  'django.contrib.sessions.middleware.SessionMiddleware',
>>  'django.middleware.csrf.CsrfViewMiddleware',
>>  'django.contrib.auth.middleware.AuthenticationMiddleware',
>>  'django.contrib.messages.middleware.MessageMiddleware')
>>
>>
>> Traceback:
>> File "C:\Python27-32\lib\site-packages\django\core\handlers\base.py" in
>> get_response
>>   111.                         response = callback(request,
>> *callback_args, **callback_kwargs)
>> File "C:\Python27-32\lib\site-packages\django\contrib\auth\decorators.py"
>> in _wrapped_view
>>   20.                 return view_func(request, *args, **kwargs)
>> File
>> "C:\Users\ldevocht\git\DynResAlignRepo\dynresalign\leden\profiler\persistence.py"
>> in addUserAccountToPerson
>>   189.     person.load()
>> File
>> "c:\python27-32\lib\site-packages\surf-1.1.6r0_r374-py2.7.egg\surf\resource\__init__.py"
>> in load
>>   548.         self.__set_predicate_values(results_d, True)
>> File
>> "c:\python27-32\lib\site-packages\surf-1.1.6r0_r374-py2.7.egg\surf\resource\__init__.py"
>> in __set_predicate_values
>>   571.         for p, v in results.items():
>>
>> Exception Type: AttributeError at /leden/done/
>> Exception Value: 'list' object has no attribute 'items'
>>
>> I assume that results.items() is something that comes from the
>> SPARQLWrapper en then handled by SurfRDF. However it is impossible for me to
>> tell what exactly happens when an empty result is being returned in
>> SPARQLWrapper.
>>
>> The code that handles this is:
>>
>> def __set_predicate_values(self, results, direct):
>>         """ set the prediate - value(s) to the resource using lazy
>> loading,
>>         `results` is a dict under the form:
>>         {'predicate':{'value':[concept,concept],...},...}.
>>
>>         """
>>
>>         for p, v in results.items():
>>             attr = rdf2attr(p, direct)
>>             value = self._lazy(v)
>>             if value:
>>                 self.__setattr__(attr, value) So I assume that if
>> SPARQLWrapper makes sure that the results or the results.items() object is
>> never simply empty or that the results have always at least an attribute
>> items this issue can be resolved even when the results are empty (which is
>> obviously the case here).v
>> Any comments on this issue or at least a workaround or something?
>>
>>
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>
>
>
> --
>
> Sergio Fernández <se...@wi...>



-- 

Sergio Fernández <se...@wi...>