python - 使用 'or' 合并查询集时，两侧不能有 extra(select=...)

Question

我认为这是一个简单直接的问题，我有两个查询集，我将它们合并为一个。 但发生了这个错误。

When merging querysets using 'or', you cannot have extra(select=...) on both sides.

代码:

projects = pending_or_onhold | pending_by_manager

回溯

Traceback (most recent call last):
  File "C:\Python27\lib\site-packages\django\core\handlers\base.py", line 115, in get_response
    response = callback(request, *callback_args, **callback_kwargs)
  File "C:\Python27\lib\site-packages\django\contrib\auth\decorators.py", line 25, in _wrapped_view
    return view_func(request, *args, **kwargs)
  File "D:/Pythonapps/ifscoatings\ifs_request_system\decorators.py", line 20, in inner
    return view(request, *args, **kwargs)
  File "D:/Pythonapps/ifscoatings\request_system\views.py", line 493, in dashboard
    return render_to_response('dashboard.html', context_instance=RequestContext(request, ctx))
  File "C:\Python27\lib\site-packages\django\shortcuts\__init__.py", line 29, in render_to_response
    return HttpResponse(loader.render_to_string(*args, **kwargs), **httpresponse_kwargs)
  File "C:\Python27\lib\site-packages\django\template\loader.py", line 177, in render_to_string
    return t.render(context_instance)
  File "C:\Python27\lib\site-packages\django\template\base.py", line 140, in render
    return self._render(context)
  File "C:\Python27\lib\site-packages\django\template\base.py", line 134, in _render
    return self.nodelist.render(context)
  File "C:\Python27\lib\site-packages\django\template\base.py", line 830, in render
    bit = self.render_node(node, context)
  File "C:\Python27\lib\site-packages\django\template\debug.py", line 74, in render_node
    return node.render(context)
  File "C:\Python27\lib\site-packages\django\template\loader_tags.py", line 124, in render
    return compiled_parent._render(context)
  File "C:\Python27\lib\site-packages\django\template\base.py", line 134, in _render
    return self.nodelist.render(context)
  File "C:\Python27\lib\site-packages\django\template\base.py", line 830, in render
    bit = self.render_node(node, context)
  File "C:\Python27\lib\site-packages\django\template\debug.py", line 74, in render_node
    return node.render(context)
  File "C:\Python27\lib\site-packages\django\template\loader_tags.py", line 63, in render
    result = block.nodelist.render(context)
  File "C:\Python27\lib\site-packages\django\template\base.py", line 830, in render
    bit = self.render_node(node, context)
  File "C:\Python27\lib\site-packages\django\template\debug.py", line 74, in render_node
    return node.render(context)
  File "C:\Python27\lib\site-packages\django\template\defaulttags.py", line 483, in render
    output = self.nodelist.render(context)
  File "C:\Python27\lib\site-packages\django\template\base.py", line 830, in render
    bit = self.render_node(node, context)
  File "C:\Python27\lib\site-packages\django\template\debug.py", line 74, in render_node
    return node.render(context)
  File "C:\Python27\lib\site-packages\django\template\defaulttags.py", line 284, in render
    return nodelist.render(context)
  File "C:\Python27\lib\site-packages\django\template\base.py", line 830, in render
    bit = self.render_node(node, context)
  File "C:\Python27\lib\site-packages\django\template\debug.py", line 74, in render_node
    return node.render(context)
  File "C:\Python27\lib\site-packages\django\template\loader_tags.py", line 156, in render
    return self.render_template(self.template, context)
  File "C:\Python27\lib\site-packages\django\template\loader_tags.py", line 138, in render_template
    output = template.render(context)
  File "C:\Python27\lib\site-packages\django\template\base.py", line 140, in render
    return self._render(context)
  File "C:\Python27\lib\site-packages\django\template\base.py", line 134, in _render
    return self.nodelist.render(context)
  File "C:\Python27\lib\site-packages\django\template\base.py", line 830, in render
    bit = self.render_node(node, context)
  File "C:\Python27\lib\site-packages\django\template\debug.py", line 74, in render_node
    return node.render(context)
  File "C:\Python27\lib\site-packages\django\template\defaulttags.py", line 483, in render
    output = self.nodelist.render(context)
  File "C:\Python27\lib\site-packages\django\template\base.py", line 830, in render
    bit = self.render_node(node, context)
  File "C:\Python27\lib\site-packages\django\template\debug.py", line 74, in render_node
    return node.render(context)
  File "C:\Python27\lib\site-packages\django\template\defaulttags.py", line 481, in render
    six.iteritems(self.extra_context)])
  File "C:\Python27\lib\site-packages\django\template\base.py", line 606, in resolve
    new_obj = func(obj, *arg_vals)
  File "D:/Pythonapps/ifscoatings\request_system\templatetags\template_filters.py", line 54, in filter_project
    projects = safe_projects(project_list=_callable(MyDashboard(request=request)), request=request, filter_market=True)
  File "D:/Pythonapps/ifscoatings\request_system\lib.py", line 73, in chemist_pending_work
    projects = pending_or_onhold | pending_by_manager
  File "C:\Python27\lib\site-packages\django\db\models\query.py", line 234, in __or__
    combined.query.combine(other.query, sql.OR)
  File "C:\Python27\lib\site-packages\django\db\models\sql\query.py", line 544, in combine
    raise ValueError("When merging querysets using 'or', you "
ValueError: When merging querysets using 'or', you cannot have extra(select=...) on both sides.
[05/Dec/2013 17:37:05] "GET /dashboard/ HTTP/1.1" 500 655503

这是选择的 Exta，它正在创建我不能拥有的错误。 这是发现的新错误。我只想合并两个查询集。

.....filter().extra(
                select={"priority": "COALESCE(bm_rank, sales_rank, id)", "size": "order_size_price*order_size_weight"})

Answer 1

请仔细阅读您发布的错误消息。 Django 不支持使用额外的 select 合并计算的 QuerySet(两者)。

我还没有看到你的其余代码，或者更多的代码，让我可以描绘出你正在工作的上下文。

我建议您使用一些自定义生成器。然后再试一次。

您还可以尝试使用原始 SQL。