Here comes the sorting app.

sortingtest/sorting/models.py

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+from django.db import models
+
+# Create your models here.

sortingtest/sorting/templates/sorting/sort_link_frag.html

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+<a href="./?sort_by={% if visible_name %}{{visible_name}}{% else %}{{ sort_field }}{% endif %}{{ extra_vars }}">
+{{ link_text }}
+</a>

sortingtest/sorting/templatetags/sorting.py

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+from django import template
+
+register = template.Library()
+
+@register.inclusion_tag('sorting/sort_link_frag.html', takes_context=True)            
+def sort_link(context, link_text, sort_field, visible_name=None):
+    """Usage: {% sort_link "link text" "field_name" %}
+    Usage: {% sort_link "link text" "field_name" "Visible name" %}
+    """
+    is_sorted = False
+    sort_order = None
+    orig_sort_field = sort_field
+    if context.get('current_sort_field') == sort_field:
+        sort_field = '-%s'%sort_field
+        visible_name = '-%s'%(visible_name or orig_sort_field)
+        is_sorted = True
+        sort_order = 'down'
+    elif context.get('current_sort_field') == '-'+sort_field:
+        visible_name = '%s'%(visible_name or orig_sort_field)
+        is_sorted = True
+        sort_order = 'up'
+
+    if visible_name:
+        if 'request' in context:
+            request = context['request']
+            request.session[visible_name] = sort_field
+
+    if 'getsortvars' in context:
+        extra_vars = context['getsortvars']
+    else:
+        if 'request' in context:
+            request = context['request']
+            getvars = request.GET.copy()
+            if 'sort_by' in getvars:
+                del getvars['sort_by']
+            if len(getvars.keys()) > 0:
+                context['getsortvars'] = "&%s" % getvars.urlencode()
+            else:
+                context['getsortvars'] = ''
+            extra_vars = context['getsortvars']
+
+        else:
+            extra_vars = ''
+
+
+    return {'link_text':link_text, 'sort_field':sort_field, 'extra_vars':extra_vars,
+            'sort_order':sort_order, 'is_sorted':is_sorted, 'visible_name':visible_name
+            }
+
+
+@register.tag
+def auto_sort(parser, token):
+    "usage: {% auto_sort queryset %}"
+    try:
+        tag_name, queryset = token.split_contents()
+    except ValueError:
+        raise template.TemplateSyntaxError, "%r tag requires a single argument" % token.contents.split()[0]
+    return SortedQuerysetNode(queryset)
+
+class SortedQuerysetNode(template.Node):
+    def __init__(self, queryset):
+        self.queryset_var = queryset
+        self.queryset = template.Variable(queryset)
+
+    def render(self, context):
+        queryset = self.queryset.resolve(context)
+        if 'request' in context:
+            request = context['request']
+            sort_by = request.GET.get('sort_by')
+            has_visible_name = False
+            if sort_by:
+                if sort_by in [el.name for el in queryset.model._meta.fields]:
+                    queryset = queryset.order_by(sort_by)
+                else:
+                    has_visible_name = True
+                    if sort_by in request.session:
+                        sort_by = request.session[sort_by]
+                        try:
+                            queryset = queryset.order_by(sort_by)
+                        except:
+                            raise
+        context[self.queryset_var] = queryset
+        if 'request' in context:
+            getvars = request.GET.copy()
+        else:
+            getvars = {}
+        if 'sort_by' in getvars:
+            if has_visible_name:
+                context['current_sort_field']= request.session.get(getvars['sort_by']) or getvars['sort_by'] 
+            else:
+                context['current_sort_field']= getvars['sort_by']
+            del getvars['sort_by']
+        if len(getvars.keys()) > 0:
+            context['getsortvars'] = "&%s" % getvars.urlencode()
+        else:
+            context['getsortvars'] = ''
+        return ''
+
+
+
+

sortingtest/sorting/tests.py

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+"""
+This file demonstrates two different styles of tests (one doctest and one
+unittest). These will both pass when you run "manage.py test".
+
+Replace these with more appropriate tests for your application.
+"""
+
+from django.test import TestCase
+
+class SimpleTest(TestCase):
+    def test_basic_addition(self):
+        """
+        Tests that 1 + 1 always equals 2.
+        """
+        self.failUnlessEqual(1 + 1, 2)
+
+__test__ = {"doctest": """
+Another way to test that 1 + 1 is equal to 2.
+
+>>> 1 + 1 == 2
+True
+"""}
+

sortingtest/sorting/views.py

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+