Changes between Initial Version and Version 1 of SortedIntThenAlpha

Timestamp:

Oct 20, 2006, 1:48:36 PM (18 years ago)

Author:

davidschein@…

Comment:

--

SortedIntThenAlpha

@@ +1 @@
+There are times when a Char field can have number and alpha values and you want them sorted such that the numbers come out in numeric rather than alphanumeric order followed by the text values.
+
+For example, academic course sections may be named 1, 2, 14, A, B, C, and so on (not my decision, I should add.)  So we have
+{{{
+#!python
+class Section(models.Model):
+    name = models.CharField(maxlength=3)
+    schedule_course = models.ForeignKey(ScheduleCourse)
+    instructors = models.ManyToManyField(Contact)
+    ...
+}}}
+
+When we list the sections we want to see something like:
+{{{
+2       LEC: W  6:30pm-9:20pm   
+14      LEC: Th 6:30pm-9:20pm   
+A       LEC: M W F      10:00am-10:50am 
+B       LEC: M W F      11:00am-11:50am 
+}}}
+rather than the alphanumerically ordered:
+{{{
+14      LEC: Th 6:30pm-9:20pm   
+2       LEC: W  6:30pm-9:20pm   
+A       LEC: M W F      10:00am-10:50am 
+B       LEC: M W F      11:00am-11:50am 
+}}}
+
+We accomplish this with a template tag as in {{{{% for section in sc.section_set.all|sorted_int_then_alpha:"name" %}}}}.
+
+The code for {{{sorted_int_then_alpha}}} follows:
+{{{
+#!python
+from django import template
+from itertools import chain
+from operator import attrgetter
+
+register = template.Library()
+
+@register.filter
+def sorted_int_then_alpha(items, attr):
+    """ Return items sorted on attr where int values come first and 
+        in numerical order followed by anything else in aplhanumeric ordering
+    """
+    key = attrgetter(attr)
+    sorted_ints = sorted([(int(key(item)),item) for item in items if item.name.isdigit()])
+    sorted_strs = sorted([(key(item),item) for item in items if not item.name.isdigit()])
+    return [item for (_sorter, item) in chain(sorted_ints, sorted_strs)]    
+}}}