From fec342df5a9c6967787c9b4304da5a3b20d184c6 Mon Sep 17 00:00:00 2001
From: Őry Máté <ory.mate@cloud.bme.hu>
Date: Wed, 19 Mar 2014 00:13:14 +0100
Subject: [PATCH] common: add HumanSortField
---
circle/common/models.py | 76 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 76 insertions(+)
diff --git a/circle/common/models.py b/circle/common/models.py
index 8701698..ecbc922 100644
--- a/circle/common/models.py
+++ b/circle/common/models.py
@@ -1,3 +1,4 @@
+from collections import deque
from hashlib import sha224
from logging import getLogger
from time import time
@@ -139,3 +140,78 @@ def method_cache(memcached_seconds=60, instance_seconds=5): # noqa
return x
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
+ names.)
+
+ 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]):
+ match.append(s.popleft())
+ while s and not pred(s[0]):
+ notmatch.append(s.popleft())
+ 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(
+ self.get_monitored_value(model_instance))
+ 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
+try:
+ from south.modelsinspector import add_introspection_rules
+ add_introspection_rules(rules=[
+ (
+ (HumanSortField,),
+ [],
+ {'monitor': ('monitor', {}),
+ 'maximum_number_length': ('maximum_number_length', {}), }
+ ),
+ ], patterns=['common\.models\.'])
+except ImportError:
+ pass
--
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