order_by for a related table generates wrong query if the requested ordering field has the same name as the related class

[Nikolaus Schlemm <nikl@…>]

reproducible by:

1. start an app "orderbug" with the following models:

   class Category(models.Model):
       category = models.CharField(maxlength=255)
   
   
   class Post(models.Model):
       category = models.ForeignKey(Category)
   

2. install it
3. run the following in the interpreter

   In [1]: from orderbug.models import Post
   
   In [2]: Post.objects.order_by('orderbug_category.category')
   ---------------------------------------------------------------------------
   pysqlite2.dbapi2.OperationalError                          Traceback (most recent call last)
   
   /home/nikl/dev/django/testproject/<ipython console> 
   
   /usr/lib/python2.4/site-packages/IPython/Prompts.py in __call__(self, arg)
       512 
       513             # and now call a possibly user-defined print mechanism
   --> 514             manipulated_val = self.display(arg)
       515             
       516             # user display hooks can change the variable to be stored in
   
   /usr/lib/python2.4/site-packages/IPython/Prompts.py in _display(self, arg)
       536         """
       537 
   --> 538         return self.shell.hooks.result_display(arg)
       539 
       540     # Assign the default display method:
   
   /usr/lib/python2.4/site-packages/IPython/hooks.py in __call__(self, *args, **kw)
       131             #print "prio",prio,"cmd",cmd #dbg
       132             try:
   --> 133                 ret = cmd(*args, **kw)
       134                 return ret
       135             except ipapi.TryNext, exc:
   
   /usr/lib/python2.4/site-packages/IPython/hooks.py in result_display(self, arg)
       152     
       153     if self.rc.pprint:
   --> 154         out = pformat(arg)
       155         if '\n' in out:
       156             # So that multi-line strings line up with the left column of
   
   /home/nikl/dev/django/testproject/pprint.py in pformat(self, object)
       108     def pformat(self, object):
       109         sio = _StringIO()
   --> 110         self._format(object, sio, 0, 0, {}, 0)
       111         return sio.getvalue()
       112 
   
   /home/nikl/dev/django/testproject/pprint.py in _format(self, object, stream, indent, allowance, context, level)
       126             self._readable = False
       127             return
   --> 128         rep = self._repr(object, context, level - 1)
       129         typ = _type(object)
       130         sepLines = _len(rep) > (self._width - 1 - indent - allowance)
   
   /home/nikl/dev/django/testproject/pprint.py in _repr(self, object, context, level)
       192     def _repr(self, object, context, level):
       193         repr, readable, recursive = self.format(object, context.copy(),
   --> 194                                                 self._depth, level)
       195         if not readable:
       196             self._readable = False
   
   /home/nikl/dev/django/testproject/pprint.py in format(self, object, context, maxlevels, level)
       204         and whether the object represents a recursive construct.
       205         """
   --> 206         return _safe_repr(object, context, maxlevels, level)
       207 
       208 
   
   /home/nikl/dev/django/testproject/pprint.py in _safe_repr(object, context, maxlevels, level)
       289         return format % _commajoin(components), readable, recursive
       290 
   --> 291     rep = repr(object)
       292     return rep, (rep and not rep.startswith('<')), False
       293 
   
   /home/nikl/site-packages/django/db/models/query.py in __repr__(self)
        95 
        96     def __repr__(self):
   ---> 97         return repr(self._get_data())
        98 
        99     def __len__(self):
   
   /home/nikl/site-packages/django/db/models/query.py in _get_data(self)
       428     def _get_data(self):
       429         if self._result_cache is None:
   --> 430             self._result_cache = list(self.iterator())
       431         return self._result_cache
       432 
   
   /home/nikl/site-packages/django/db/models/query.py in iterator(self)
       170         cursor = connection.cursor()
       171         select, sql, params = self._get_sql_clause()
   --> 172         cursor.execute("SELECT " + (self._distinct and "DISTINCT " or "") + ",".join(select) + sql, params)
       173         fill_cache = self._select_related
       174         index_end = len(self.model._meta.fields)
   
   /home/nikl/site-packages/django/db/backends/util.py in execute(self, sql, params)
        10         start = time()
        11         try:
   ---> 12             return self.cursor.execute(sql, params)
        13         finally:
        14             stop = time()
   
   /home/nikl/site-packages/django/db/backends/sqlite3/base.py in execute(self, query, params)
        90     def execute(self, query, params=()):
        91         query = self.convert_query(query, len(params))
   ---> 92         return Database.Cursor.execute(self, query, params)
        93 
        94     def executemany(self, query, param_list):
   
   OperationalError: no such column: orderbug_category.category_id
   

[(none)]

Milestone Version 1.0 deleted

[mir@…]

duplicate of #2210

The correct usage in your case is order_by('category__category'). This does not currently work, but #2210 is about the same thing (and has a working patch!)