Commit fec342df by Őry Máté

common: add HumanSortField

parent bedb2e12
from collections import deque
from hashlib import sha224 from hashlib import sha224
from logging import getLogger from logging import getLogger
from time import time from time import time
...@@ -139,3 +140,78 @@ def method_cache(memcached_seconds=60, instance_seconds=5): # noqa ...@@ -139,3 +140,78 @@ def method_cache(memcached_seconds=60, instance_seconds=5): # noqa
return x return x
return inner_cache return inner_cache
class HumanSortField(CharField):
A CharField that monitors another field on the same model and sets itself
to a normalized value, which can be used for sensible lexicographycal
sorting for fields containing numerals. (Avoiding technically correct
orderings like [a1, a10, a2], which can be annoying for file or host
Apart from CharField's default arguments, an argument is requered:
- monitor sets the base field, whose value is normalized.
- maximum_number_length can also be provided, and defaults to 4. If
you have to sort values containing numbers greater than 9999, you
should increase it.
Code is based on carljm's django-model-utils.
def __init__(self, *args, **kwargs):
logger.debug('Initing HumanSortField(%s %s)',
unicode(args), unicode(kwargs))
kwargs.setdefault('default', "")
self.maximum_number_length = kwargs.pop('maximum_number_length', 4)
monitor = kwargs.pop('monitor', None)
if not monitor:
raise TypeError(
'%s requires a "monitor" argument' % self.__class__.__name__)
self.monitor = monitor
kwargs['blank'] = True
super(HumanSortField, self).__init__(*args, **kwargs)
def get_monitored_value(self, instance):
return getattr(instance, self.monitor)
def get_normalized_value(self, val):
def partition(s, pred):
match, notmatch = deque(), deque()
while s and pred(s[0]):
while s and not pred(s[0]):
return (''.join(match), ''.join(notmatch), s)
logger.debug('Normalizing value: %s', val)
norm = ""
val = deque(val)
while val:
numbers, letters, val = partition(val, lambda s: s[0].isdigit())
norm += numbers and numbers.rjust(self.maximum_number_length, '0')
norm += letters
logger.debug('Normalized value: %s', norm)
return norm
def pre_save(self, model_instance, add):
logger.debug('Pre-saving %s.%s. %s',
model_instance, self.attname, add)
value = self.get_normalized_value(
setattr(model_instance, self.attname, value[:self.max_length])
return super(HumanSortField, self).pre_save(model_instance, add)
# allow South to handle these fields smoothly
from south.modelsinspector import add_introspection_rules
{'monitor': ('monitor', {}),
'maximum_number_length': ('maximum_number_length', {}), }
], patterns=['common\.models\.'])
except ImportError:
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