Django 1.8 - FieldError：无法将关键字解析为字段

Question

我最近从 Django 1.6 升级到了 Django 1.8。当我这样做时，我发现我不再能够通过外键关系进行查找，如下所述： https://docs.djangoproject.com/en/1.8/topics/db/queries/#lookups-that-span-relationships.

系统设置为有两个项目使用同一个数据库。 （不是我的想法，但我现在不想更改。）最初创建和迁移模型的项目在升级后工作得很好，但另一个没有。每个的模型文件都是相同的。

模型.py：

class Site(models.Model):
    name = models.CharField(max_length=255)

    class Meta:
        app_label = 'project1'

class Page(models.Model):
    title = models.CharField(max_length=255)
    site = models.ForeignKey('Site')

    class Meta:
        app_label = 'project1'

来自 Django Shell 的错误回溯：

>>> x = models.Site.objects.filter(page__id=1000)
Traceback (most recent call last):
  File "<console>", line 1, in <module>
  File "/home/user_name/project2/venv/local/lib/python2.7/site-packages/django/db/models/manager.py", line 127, in manager_method
    return getattr(self.get_queryset(), name)(*args, **kwargs)
  File "/home/user_name/project2/venv/local/lib/python2.7/site-packages/django/db/models/query.py", line 679, in filter
    return self._filter_or_exclude(False, *args, **kwargs)
  File "/home/user_name/project2/venv/local/lib/python2.7/site-packages/django/db/models/query.py", line 697, in _filter_or_exclude
    clone.query.add_q(Q(*args, **kwargs))
  File "/home/user_name/project2/venv/local/lib/python2.7/site-packages/django/db/models/sql/query.py", line 1314, in add_q
    clause, require_inner = self._add_q(where_part, self.used_aliases)
  File "/home/user_name/project2/venv/local/lib/python2.7/site-packages/django/db/models/sql/query.py", line 1342, in _add_q
    allow_joins=allow_joins, split_subq=split_subq,
  File "/home/user_name/project2/venv/local/lib/python2.7/site-packages/django/db/models/sql/query.py", line 1154, in build_filter
    lookups, parts, reffed_expression = self.solve_lookup_type(arg)
  File "/home/user_name/project2/venv/local/lib/python2.7/site-packages/django/db/models/sql/query.py", line 1035, in solve_lookup_type
    _, field, _, lookup_parts = self.names_to_path(lookup_splitted, self.get_meta())
  File "/home/user_name/project2/venv/local/lib/python2.7/site-packages/django/db/models/sql/query.py", line 1401, in names_to_path
    "Choices are: %s" % (name, ", ".join(available)))
FieldError: Cannot resolve keyword 'page' into field. Choices are: name, id

在第一个项目中，相同的查询按预期工作：

>>> x = models.Site.objects.filter(page__id=1000)
[<Site: http://stackoverflow.com>]

Answer 1

我是 Django 新手，不知道这是否有帮助，但我遇到了同样的问题。就我而言，这是输入错误。

我之前写过这个：

Question.objects.filter(question_text_startswith='What')

在 Django 文档中，我注意到在查找 startswith 之前应该有 2 个下划线：

Question.objects.filter(question_text__startswith='What')

Answer 2

如果您在 `ForeignKey 上设置 related_name 会怎样？

class Page(models.Model):
    site = models.ForeignKey('Site', related_name="pages")  # Note the related_name here

我在另一个项目上尝试过，它按预期工作：

>>> Site.objects.filter(pages__pk=42)
[<Site: http://stackoverflow.com>]

如果不设置related_name，我认为默认是<model>_set。所以应该是page_set。