我根本不了解的 Django 模型的一个方面是相关字段,并正确使用它们。我认为这反映了对 SQL 和数据库的一般理解不足 - 所以我怀疑这是许多 django 用户的问题。
在我当前的代码中,我正在构建一个旅游应用程序,所以我有住宿作为模型。然后我有路线。一天的路线最终是一堆关系字段,但让我感到困惑的是我需要一个开始住宿和一个结束住宿 - 两个独立的关系。
对我来说,从逻辑上讲,我应该能够有一个 OneToOneField - start_accom 到住宿,然后 end_accom 到住宿。但是这样做会引发错误。
编码:
class Route(models.Model):
start_accom = models.OneToOneField(
Accommodation,
on_delete=models.CASCADE,
primary_key=True,
)
end_accom = models.OneToOneField(
Accommodation,
on_delete=models.CASCADE,
)
mode_of_travel = models.CharField(max_length=50)
description = models.TextField()
当我运行 django runserver 时出现错误消息:
Performing system checks...
Unhandled exception in thread started by <function check_errors.<locals>.wrapper at 0x103ecdd90>
Traceback (most recent call last):
File "/Users/vernonswanepoel/.virtualenvs/tour/lib/python3.6/site-packages/django/utils/autoreload.py", line 226, in wrapper
fn(*args, **kwargs)
File "/Users/vernonswanepoel/.virtualenvs/tour/lib/python3.6/site-packages/django/core/management/commands/runserver.py", line 121, in inner_run
self.check(display_num_errors=True)
File "/Users/vernonswanepoel/.virtualenvs/tour/lib/python3.6/site-packages/django/core/management/base.py", line 431, in check
raise SystemCheckError(msg)
django.core.management.base.SystemCheckError: SystemCheckError: System check identified some issues:
ERRORS:
company.Route.end_accom: (fields.E304) Reverse accessor for 'Route.end_accom' clashes with reverse accessor for 'Route.start_accom'.
HINT: Add or change a related_name argument to the definition for 'Route.end_accom' or 'Route.start_accom'.
company.Route.end_accom: (fields.E305) Reverse query name for 'Route.end_accom' clashes with reverse query name for 'Route.start_accom'.
HINT: Add or change a related_name argument to the definition for 'Route.end_accom' or 'Route.start_accom'.
company.Route.start_accom: (fields.E304) Reverse accessor for 'Route.start_accom' clashes with reverse accessor for 'Route.end_accom'.
HINT: Add or change a related_name argument to the definition for 'Route.start_accom' or 'Route.end_accom'.
company.Route.start_accom: (fields.E305) Reverse query name for 'Route.start_accom' clashes with reverse query name for 'Route.end_accom'.
HINT: Add or change a related_name argument to the definition for 'Route.start_accom' or 'Route.end_accom'.
System check identified 4 issues (0 silenced).