django - 未分配 Django SearchRank 注释，生产中有错误，但开发中没有

Question

我的 Django 应用程序（带有 Postgres 后端的 Apache/WSGI）在生产中遇到错误，我无法在 dev 中重现该错误，也无法在生产机器上使用 Django shell。我该如何调试呢？

该应用程序有一个 Story 模型

class Story(models.Model): 
    title = models.CharField(max_length=400)
    content = models.TextField(blank=True) 
    quality = models.FloatField(default=0)
    search = SearchVectorField(null=True)

带有要search在保存时填充的信号：

@receiver(post_save, sender=Story) 
def update_search_vector(sender, instance, **kwargs):
   Story.objects.filter(pk=instance.pk).update(search=SearchVector('title', 'content'))

当用户搜索时，我想返回相关且高质量的结果。我将分数指定为这两个值的调和平均值：

query = SearchQuery(form.cleaned_data['query'])
stories = stories.annotate(
    rank=SearchRank(F('search'), query),
    score=F('rank') * F('quality') / (F('rank') + F('quality'))
).filter(rank__gte=SEARCH_RANK_CUTOFF).order_by('-score')

这在开发人员和生产环境中的 Django shell 上运行良好。但是当通过正在运行的应用程序执行时，会引发以下错误：django.core.exceptions.FieldError: Cannot resolve keyword 'rank' into field.

我无法弄清楚如何调试它。会不会是某种错误的查询集缓存？

这是完整的错误回溯：

ERROR 2019-05-21 11:59:03,388 Internal Server Error: /stories
Traceback (most recent call last):
File "/usr/local/lib/python3.5/dist-packages/django/core/handlers/exception.py", line 34, in inner
  response = get_response(request)
File "/usr/local/lib/python3.5/dist-packages/django/core/handlers/base.py", line 115, in _get_response
  response = self.process_exception_by_middleware(e, request)
File "/usr/local/lib/python3.5/dist-packages/django/core/handlers/base.py", line 113, in _get_response
  response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "/opt/myapp/myapp/views.py", line 75, in browse
  score=F('rank') * F('quality') / (F('rank') + F('quality'))
File "/usr/local/lib/python3.5/dist-packages/django/db/models/query.py", line 1056, in annotate
  clone.query.add_annotation(annotation, alias, is_summary=False)
File "/usr/local/lib/python3.5/dist-packages/django/db/models/sql/query.py", line 1000, in add_annotation
  summarize=is_summary)
File "/usr/local/lib/python3.5/dist-packages/django/db/models/expressions.py", line 446, in resolve_expression
  c.lhs = c.lhs.resolve_expression(query, allow_joins, reuse, summarize, for_save)
File "/usr/local/lib/python3.5/dist-packages/django/db/models/expressions.py", line 446, in resolve_expression
  c.lhs = c.lhs.resolve_expression(query, allow_joins, reuse, summarize, for_save)
File "/usr/local/lib/python3.5/dist-packages/django/db/models/expressions.py", line 511, in resolve_expression
  return query.resolve_ref(self.name, allow_joins, reuse, summarize, simple_col)
File "/usr/local/lib/python3.5/dist-packages/django/db/models/sql/query.py", line 1601, in resolve_ref
  join_info = self.setup_joins(field_list, self.get_meta(), self.get_initial_alias(), can_reuse=reuse)
File "/usr/local/lib/python3.5/dist-packages/django/db/models/sql/query.py", line 1504, in setup_joins
  names[:pivot], opts, allow_many, fail_on_missing=True,
File "/usr/local/lib/python3.5/dist-packages/django/db/models/sql/query.py", line 1420, in names_to_path
  "Choices are: %s" % (name, ", ".join(available)))
django.core.exceptions.FieldError: Cannot resolve keyword 'rank' into field. Choices are: content, id, quality, search, title

我安装了相同的依赖版本（通过requirements.txt），但我注意到生产运行 python3.5.2 而开发运行 3.7.3。（并且可能libapache2-mod-wsgi-py3调用另一个版本？）这似乎是一个可以探索的地方，但我不明白如果rank没有另一个例外，注释添加会如何失败。

标签： djangopostgresqlsearchannotationsdjango-queryset