def picked(self):
"""
returns a query set of picked objects using inclusion and exclusion filters
"""
try:
model, fs = manifest.get_for_picking(self.content)
except (NameError, TypeError):
return {}
cache_key = "conduit:dp:ids:{0:d}".format(self.pk)
cached_ids = cache.get(cache_key, None)
if cached_ids:
qs = model.objects.filter(pk__in=cached_ids)
else:
logger.debug("cache miss on {0:>s}".format(cache_key))
qs = model.objects.all()
#first we handle any static defers - performance optimisation
if fs and hasattr(fs, 'static_defer') and callable(fs.static_defer):
defer = fs.static_defer()
qs = qs.defer(*defer)
#second we handle any static select_related fields - performance optimisation
if fs and hasattr(fs, 'static_select_related') and callable(fs.static_select_related):
select_related = fs.static_select_related()
qs = qs.select_related(*select_related)
#third we handle any static prefetch_related fields - performance optimisation
if fs and hasattr(fs, 'static_prefetch_related') and callable(fs.static_prefetch_related):
prefetch_related = fs.static_prefetch_related()
qs = qs.prefetch_related(*prefetch_related)
# if we got our initial list from the cache, we can return it without running the expensive filters
if cached_ids:
return qs
#fourth we apply our inclusion filters
if self.include_filters:
try:
for f in self.include_filters:
if not f:
continue
coerce_filters(f)
qs = qs.filter(**f)
except ValueError, e:
logger.error("Value Error. Failure to apply include filters on on [%d] %s. %s" % (self.pk, self.name, e))
return model.objects.None()
except FieldError, e:
logger.error("Field Error. Failure to apply include filters on on [%d] %s. %s" % (self.pk, self.name, e))
return model.objects.None()
except ValueError, e:
logger.error("Value Error. Failure to apply include filters on on [%d] %s. %s" % (self.pk, self.name, e))
return model.objects.None()
except FieldError, e:
logger.error("Field Error. Failure to apply include filters on on [%d] %s. %s" % (self.pk, self.name, e))
return model.objects.None()
except Exception, e:
logger.error("failure to coerce include filters on [%d] %s. %s" % (self.pk, self.name, e))
#fifth we apply our exclusion filters
if self.exclude_filters:
try:
for f in self.exclude_filters:
if not f:
continue
coerce_filters(f)
qs = qs.exclude(**f)
except ValueError, e:
logger.error("Value Error. Failure to apply exclude filters on on [%d] %s. %s" % (self.pk, self.name, e))
return model.objects.None()
except FieldError, e:
logger.error("Field Error. Failure to apply exclude filters on on [%d] %s. %s" % (self.pk, self.name, e))
return model.objects.None()
except Exception, e:
logger.error("failure to coerce exclude filters on [%d] %s. %s" % (self.pk, self.name, e))
#before we limit the qs we let the picking filterset apply any last minute operations
if fs and hasattr(fs, 'static_chain') and callable(fs.static_chain):
qs = fs.static_chain(qs)
#limit the qs if necessary