Fixed #3397: You can now order by non-DB fields in the admin by telling Django which field to actually order by. Thanks, marcink@elksoft.pl

git-svn-id: http://code.djangoproject.com/svn/django/trunk@4596 bcc190cf-cafb-0310-a4f2-bffc1f526a37

3 files changed, 53 insertions, 17 deletions

diff --git a/django/contrib/admin/templatetags/admin_list.py b/django/contrib/admin/templatetags/admin_list.py
index 3c0c6f0ac2..5c678fba6f 100644
--- a/django/contrib/admin/templatetags/admin_list.py
+++ b/django/contrib/admin/templatetags/admin_list.py
@@ -84,22 +84,31 @@ def result_headers(cl):
                     header = attr.short_description
                 except AttributeError:
                     header = field_name.replace('_', ' ')
-            # Non-field list_display values don't get ordering capability.
-            yield {"text": header}
+
+            # It is a non-field, but perhaps one that is sortable
+            if not getattr(getattr(cl.model, field_name), "admin_order_field", None):
+                yield {"text": header}
+                continue
+
+            # So this _is_ a sortable non-field.  Go to the yield
+            # after the else clause.
         else:
             if isinstance(f.rel, models.ManyToOneRel) and f.null:
                 yield {"text": f.verbose_name}
+                continue
             else:
-                th_classes = []
-                new_order_type = 'asc'
-                if field_name == cl.order_field:
-                    th_classes.append('sorted %sending' % cl.order_type.lower())
-                    new_order_type = {'asc': 'desc', 'desc': 'asc'}[cl.order_type.lower()]
+                header = f.verbose_name
+
+        th_classes = []
+        new_order_type = 'asc'
+        if field_name == cl.order_field:
+            th_classes.append('sorted %sending' % cl.order_type.lower())
+            new_order_type = {'asc': 'desc', 'desc': 'asc'}[cl.order_type.lower()]
 
-                yield {"text": f.verbose_name,
-                       "sortable": True,
-                       "url": cl.get_query_string({ORDER_VAR: i, ORDER_TYPE_VAR: new_order_type}),
-                       "class_attrib": (th_classes and ' class="%s"' % ' '.join(th_classes) or '')}
+        yield {"text": header,
+               "sortable": True,
+               "url": cl.get_query_string({ORDER_VAR: i, ORDER_TYPE_VAR: new_order_type}),
+               "class_attrib": (th_classes and ' class="%s"' % ' '.join(th_classes) or '')}
 
 def _boolean_icon(field_val):
     BOOLEAN_MAPPING = {True: 'yes', False: 'no', None: 'unknown'}
diff --git a/django/contrib/admin/views/main.py b/django/contrib/admin/views/main.py
index 282038e205..9fae17d5fe 100644
--- a/django/contrib/admin/views/main.py
+++ b/django/contrib/admin/views/main.py
@@ -655,10 +655,17 @@ class ChangeList(object):
             order_field, order_type = ordering[0], 'asc'
         if params.has_key(ORDER_VAR):
             try:
+                field_name = lookup_opts.admin.list_display[int(params[ORDER_VAR])]
                 try:
-                    f = lookup_opts.get_field(lookup_opts.admin.list_display[int(params[ORDER_VAR])])
+                    f = lookup_opts.get_field(field_name)
                 except models.FieldDoesNotExist:
-                    pass
+                    # see if field_name is a name of a non-field
+                    # that allows sorting
+                    try:
+                        attr = getattr(lookup_opts.admin.manager.model, field_name)
+                        order_field = attr.admin_order_field
+                    except IndexError:
+                        pass
                 else:
                     if not isinstance(f.rel, models.ManyToOneRel) or not f.null:
                         order_field = f.name
diff --git a/docs/model-api.txt b/docs/model-api.txt
index 0a10918d54..9f87d53719 100644
--- a/docs/model-api.txt
+++ b/docs/model-api.txt
@@ -1295,10 +1295,30 @@ A few special cases to note about ``list_display``:
 
           list_display = ('__str__', 'some_other_field')
 
-    * For any element of ``list_display`` that is not a field on the model, the
-      change list page will not allow ordering by that column. This is because
-      ordering is done at the database level, and Django has no way of knowing
-      how to order the result of a custom method at the SQL level.
+    * Usually, elements of ``list_display`` that aren't actual database fields
+      can't be used in sorting (because Django does all the sorting at the
+      database level).
+      
+      However, if an element of ``list_display`` represents a certain database
+      field, you can indicate this fact by setting the ``admin_order_field``
+      attribute of the item.
+      
+      For example::
+      
+        class Person(models.Model):
+            first_name = models.CharField(maxlength=50)
+            color_code = models.CharField(maxlength=6)
+
+            class Admin:
+                list_display = ('first_name', 'colored_first_name')
+
+            def colored_first_name(self):
+                return '<span style="color: #%s;">%s</span>' % (self.color_code, self.first_name)
+            colored_first_name.allow_tags = True
+            colored_first_name.admin_order_field = 'first_name'
+    
+      The above will tell Django to order by the ``first_name`` field when
+      trying to sort by ``colored_first_name`` in the admin.
 
 ``list_display_links``
 ----------------------