如何在Django中为对象设置过期时间？实现高校通知自动下架

Hey there! Let's figure out how to make your Django routine notification app auto-hide notifications after a week. Here's a step-by-step solution tailored to your code:

First, let's tweak your model to add expiration-checking logic and follow Python/PEP8 conventions (like lowercase field names, which is standard practice):

from django.db import models
from django.urls import reverse
from django.utils import timezone
from datetime import timedelta

class RoutineOrder(models.Model):
    subject = models.TextField()  # Renamed to lowercase for PEP8 compliance
    details = RichTextUploadingField()
    last_edited = models.DateTimeField(auto_now=True)
    added = models.DateTimeField(auto_now_add=True)

    def get_absolute_url(self):
        return reverse('nitwro:home')
    
    @property
    def is_expired(self):
        # Check if the notification is older than 7 days
        return timezone.now() > self.added + timedelta(days=7)
    
    class Meta:
        ordering = ['-added']  # Show newest notifications first

The is_expired property lets you quickly check if a notification should be hidden, and the Meta class ensures notifications are sorted chronologically.

Modify your view to only pass non-expired notifications to the template. We'll override get_context_data to add the filtered queryset:

from django.views.generic import TemplateView
from .models import RoutineOrder
from django.utils import timezone
from datetime import timedelta

class Home(TemplateView):
    template_name = 'nitwro/home.djt'

    def get_context_data(self, **kwargs):
        context = super().get_context_data(**kwargs)
        # Calculate the cutoff date (1 week ago from now)
        one_week_ago = timezone.now() - timedelta(days=7)
        # Fetch only notifications added within the last week
        context['active_notifications'] = RoutineOrder.objects.filter(
            added__gte=one_week_ago
        ).order_by('-added')
        return context

This ensures only valid, non-expired notifications make it to your template.

If you want to clean up old notifications from the database (instead of just hiding them), set up a scheduled task. Here's how to do it with Django Q (a lightweight task queue):

1. Install Django Q and configure it in your settings.py
2. Create a tasks.py file in your app:

from .models import RoutineOrder
from django.utils import timezone
from datetime import timedelta

def clean_expired_notifications():
    """Delete notifications older than 7 days"""
    one_week_ago = timezone.now() - timedelta(days=7)
    RoutineOrder.objects.filter(added__lt=one_week_ago).delete()

3. Schedule the task to run daily (via Django Q's admin interface or command line) to keep your database tidy.

Update your home.djt template to show the active notifications:

{% for notification in active_notifications %}
    <div class="notification-card">
        <h2>{{ notification.subject }}</h2>
        <p class="notification-date">Added on: {{ notification.added|date:"F j, Y, g:i a" }}</p>
        <div class="notification-details">{{ notification.details|safe }}</div>
    </div>
{% empty %}
    <p>No active routine notifications at this time.</p>
{% endfor %}

This will loop through valid notifications, display their content, and show a fallback message if there are none.

内容的提问来源于stack exchange，提问作者Shashwat Shukla