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Kovy Jacob's questions

Martin Hope
Kovy Jacob
Asked: 2025-01-13 01:10:47 +0800 CST
  • 5

我有一个动态 URL 配置如下：

path('segment/', func1, name='func1'),
path('segment/<str:string>/', string, name='string'),

但是，当我转到https://example.com/segment/watch?v=nTeq0U_V15U（watch?v=nTeq0U_V15U字符串）时，中间会自动添加一个斜线，使其成为https://example.com/segment/watch/?v=nTeq0U_V15U/。有趣的是，即使我没有包含 3 个段的 URL 模式，也不会引发 404 错误urls.py。但是，我的问题是为什么要添加斜线，我该如何避免它？

django
Martin Hope
Kovy Jacob
Asked: 2025-01-03 01:33:43 +0800 CST
  • 7

我这里有 3 个模型需要处理：SurveyQuestion、Update和Notification。每当创建或 的实例时，我都会使用post_save信号来创建模型的实例。NotificationSurveyQuestionUpdate

该Notification模型有一个GenericForeignKey，它指向创建它的模型。在通知模型中，我尝试使用设置ForeignKey为__str__创建title它的模型实例的字段。如下所示：

class Notification(models.Model):
    source_object = models.ForeignKey(ContentType, on_delete=models.CASCADE)
    object_id = models.PositiveIntegerField()
    source = GenericForeignKey("source_object", "object_id")
    #more stuff

    def __str__(self):
        return f'{self.source.title} notification'

我能够从管理面板创建 SurveyQuestion 和 Update 的实例，然后（应该）创建 Notification 的实例。但是，当我Notification在 shell 中查询实例时：

from hotline.models import Notification
notifications = Notification.objects.all()
for notification in notifications:
    print (f"Notification object: {notification}")

NoneType
---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
      1 for notification in notifications:
----> 2     print (notification)
File ~/ygzsey/hotline/models.py:27, in Notification.__str__(self)
     26 def __str__(self):
---> 27     return f'{self.source.title} notification'
AttributeError: 'NoneType' object has no attribute 'title'

当我查询以下实例时SurveyQuestion：

from hotline.models import SurveyQuestion
surveys = SurveyQuestion.objects.all()
for survey in surveys:
    print (f"Model: {survey.__class__.__name__}")

Model: SurveyQuestion

当我查询实例Notification并尝试打印其字段的类名ForeignKey（我将其标记为source）时，我得到了以下信息：

for notification in notifications:
    print (f"Notification for {notification.source.__class__.__name__}")

Notification for NoneType
Notification for NoneType
Notification for NoneType

因此看起来SurveyQuestion，、Update和Notification实例都保存正常，但是存在一些问题GenericForeignKey。

我已经使用post_save创建了一个实例，但是当我尝试在管理面板中保存或的实例时会出现错误：NotificationNotification(source_object=instance, start_date=instance.start_date, end_date=instance.end_date)SurveyQuestionUpdate

ValueError at /admin/hotline/update/add/
Cannot assign "<Update: Update - ad>": "Notification.source_object" must be a "ContentType" instance.

所以我将其改为Notification(source_object=ContentType.objects.get_for_model(instance), start_date=instance.start_date, end_date=instance.end_date)。

我的完整models.py：

from django.db import models
from datetime import timedelta
from django.utils import timezone
from django.contrib.contenttypes.fields import GenericForeignKey, GenericRelation
from django.contrib.contenttypes.models import ContentType
from django.db.models.signals import post_save
from django.dispatch import receiver

def tmrw():
    return timezone.now() + timedelta(days=1)

class Notification(models.Model):
    source_object = models.ForeignKey(ContentType, on_delete=models.CASCADE)
    object_id = models.PositiveIntegerField()
    source = GenericForeignKey("source_object", "object_id")
    start_date = models.DateTimeField(default=timezone.now)
    end_date = models.DateTimeField(default=tmrw)

    class Meta:
        verbose_name = 'Notification'
        verbose_name_plural = f'{verbose_name}s'

    def __str__(self):
        return f'{self.source.title} notification'

class Update(models.Model):
    title = models.CharField(max_length=25)
    update = models.TextField()
    start_date = models.DateTimeField(default=timezone.now)
    end_date = models.DateTimeField(default=tmrw)
    #notification = GenericRelation(Notification, related_query_name='notification')

    class Meta:
        verbose_name = 'Update'
        verbose_name_plural = f'{verbose_name}s'

    def __str__(self):
        return f'{self.__class__.__name__} - {self.title}'

class SurveyQuestion(models.Model):
    title = models.CharField(max_length=25)
    question = models.TextField()
    start_date = models.DateTimeField(default=timezone.now)
    end_date = models.DateTimeField(default=tmrw)
    #notification = GenericRelation(Notification, related_query_name='notification')

    class Meta:
        verbose_name = 'Survey'
        verbose_name_plural = f'{verbose_name}s'

    def __str__(self):
        return f'{self.__class__.__name__} - {self.title}'

class SurveyOption(models.Model):
    survey = models.ForeignKey(SurveyQuestion, on_delete=models.CASCADE, related_name='options')
    option = models.TextField()
    id = models.AutoField(primary_key=True)

    class Meta:
        verbose_name = 'Survey option'
        verbose_name_plural = f'{verbose_name}s'

    def __str__(self):
        return f'{self.survey.title} option #{self.id}'

@receiver(post_save)
def create_notification(instance, **kwargs):
    #"""
    print (f"instance: {instance}")
    print (f"instance.__class__: {instance.__class__}")
    print (f"instance.__class__.__name__: {instance.__class__.__name__}")
    #"""
    senders = ['SurveyQuestion', 'Update']
    if instance.__class__.__name__ in senders:
        notification = Notification(source_object=ContentType.objects.get_for_model(instance), start_date=instance.start_date, end_date=instance.end_date)
        notification.save()

post_save.connect(create_notification)
python
Martin Hope
Kovy Jacob
Asked: 2025-01-01 04:50:10 +0800 CST
  • 5

我正在尝试将模型导入我的 Django 视图，然后查询所有对象、对它们进行排序并对其进行迭代。导入模型时没有收到任何错误，但是，当尝试使用查询模型时songs = song.objects.all()#.order_by('-release_date')，我收到错误：

UnboundLocalError at /hotline/dbm
local variable 'song' referenced before assignment
/home/path/to/site/views.py, line 82, in dbm
songs = song.objects.all()#.order_by('-release_date')

我不明白问题是什么，因为变量song显然是从我的models.py文件中导入的，并且我在导入它时没有收到任何错误 - 那么为什么 Python 不能识别出song我从文件中导入的内容models.py？

我的models.py文件：

class song(models.Model):
    name = models.TextField()
    file = models.FileField()
    release_date = models.DateTimeField(default=timezone.now)

    class Meta:
        verbose_name = 'Song'
        verbose_name_plural = f'{verbose_name}s'

我的views.py文件：

#list of modules removed to keep code clean
from .models import *

@csrf_exempt
def dbm(request: HttpRequest) -> HttpResponse:
    songs = song.objects.all()#.order_by('-release_date')

    response = request.POST.get('Digits')

    if response == None:
        vr = VoiceResponse()

        vr.say("Please choose a song, and then press pound")
        vr.pause(length=1)

        with vr.gather(finish_on_key='#', timeout=6, numDigits="1") as gather:
            for song, num in songs:
                gather.pause(length=1)
                gather.say(f"For {song.name}, please press {num}")

        vr.redirect(reverse('dbm'))

        return HttpResponse(str(vr), content_type='text/xml')

    elif response != None:
        vr = VoiceResponse()
        vr.say("hi")

        return HttpResponse(str(vr), content_type='text/xml')

谢谢！

python