使用 apscheduler 为 Django 项目在 Procfile (Heroku) 中定义 Cron 作业的问题

Question

我在安排 cron 作业时遇到问题，该作业需要抓取网站并将其作为模型 (MOVIE) 的一部分存储在数据库中。

问题是模型似乎是在执行 Procfile 之前加载的。
我应该如何创建一个运行在后台内部运行的 cron 作业并将抓取的信息存储到数据库中？这是我的代码：

过程文件：

    web: python manage.py runserver 0.0.0.0:$PORT
    scheduler: python cinemas/scheduler.py

scheduler.py:

# More code above
from cinemas.models import Movie
from apscheduler.schedulers.blocking import BlockingScheduler
sched = BlockingScheduler()

@sched.scheduled_job('cron', day_of_week='mon-fri', hour=0, minutes=26)    
def get_movies_playing_now():
  global url_movies_playing_now
  Movie.objects.all().delete()
  while(url_movies_playing_now):
    title = []
    description = []
    #Create BeatifulSoup Object with url link
    s = requests.get(url_movies_playing_now, headers=headers)
    soup = bs4.BeautifulSoup(s.text, "html.parser")
    movies = soup.find_all('ul', class_='w462')[0]

    #Find Movie's title
    for movie_title in movies.find_all('h3'):
        title.append(movie_title.text)
    #Find Movie's description
    for movie_description in soup.find_all('ul',
                                           class_='w462')[0].find_all('p'):
        description.append(movie_description.text.replace(" [More]","."))

    for t, d in zip(title, description):
        m = Movie(movie_title=t, movie_description=d)
        m.save()

    #Go to the next page to find more movies
    paging = soup.find( class_='pagenating').find_all('a', class_=lambda x:
                                                      x != "inactive")
    href = ""
    for p in paging:
        if "next" in p.text.lower():
            href = p['href']
    url_movies_playing_now = href

sched.start()
# More code below

cinemas/models.py:

from django.db import models

#Create your models here.

class Movie(models.Model):
    movie_title = models.CharField(max_length=200)
    movie_description = models.CharField(max_length=20200)

这是我在作业运行时遇到的错误。

2016-11-17T17:57:06.074914+00:00 app[scheduler.1]: Traceback (most recent call last): 2016-11-17T17:57:06.074931+00:00 app[scheduler.1]: File "cinemas/scheduler.py", line 2, in 2016-11-17T17:57:06.075058+00:00 app[scheduler.1]: import cineplex 2016-11-17T17:57:06.075060+00:00 app[scheduler.1]: File "/app/cinemas/cineplex.py", line 1, in 2016-11-17T17:57:06.075173+00:00 app[scheduler.1]: from cinemas.models import Movie 2016-11-17T17:57:06.075196+00:00 app[scheduler.1]: File "/app/cinemas/models.py", line 5, in 2016-11-17T17:57:06.075295+00:00 app[scheduler.1]: class Movie(models.Model): 2016-11-17T17:57:06.075297+00:00 app[scheduler.1]: File "/app/.heroku/python/lib/python3.5/site-packages/django/db/models/base.py", line 105, in new 2016-11-17T17:57:06.075414+00:00 app[scheduler.1]: app_config = apps.get_containing_app_config(module) 2016-11-17T17:57:06.075440+00:00 app[scheduler.1]: File "/app/.heroku/python/lib/python3.5/site-packages/django/apps/registry.py", line 237, in get_containing_app_config 2016-11-17T17:57:06.075585+00:00 app[scheduler.1]:
self.check_apps_ready() 2016-11-17T17:57:06.075586+00:00 app[scheduler.1]: File "/app/.heroku/python/lib/python3.5/site-packages/django/apps/registry.py", line 124, in check_apps_ready 2016-11-17T17:57:06.075703+00:00 app[scheduler.1]: raise AppRegistryNotReady("Apps aren't loaded yet.") 2016-11-17T17:57:06.075726+00:00 app[scheduler.1]: django.core.exceptions.AppRegistryNotReady: Apps aren't loaded yet.

如果我不包含模型对象，Cron 作业工作正常。我应该如何运行这项工作每天都使用模型对象而不失败？

谢谢

Answer 1

那是因为您不能只导入 Django 包、模型等
为了正常工作，Django 内部需要初始化，这是从 manage.py 触发的。

与其尝试自己重新创建所有这些，我总是将长运行、非网络命令写成custom management command。

例如，如果您的应用是 cinemas，您将：

创建./cinemas/management/commands/scheduler.py.
在该文件中，创建一个子class django.core.management.base.BaseCommand（子class必须被称为Command）
在 class 中，覆盖 handle()。在您的情况下，这就是您调用 sched.start()
你的 Procfile 将有 scheduler: python manage.py scheduler

希望对您有所帮助。

Answer 2

您可以通过在 sceduler.py

的顶部添加以下行来解决问题

import django
django.setup()

在 django 文档中 it says

If you’re using components of Django “standalone” – for example, writing a Python script which loads some Django templates and renders them, or uses the ORM to fetch some data – there’s one more step you’ll need in addition to configuring settings.

After you’ve either set DJANGO_SETTINGS_MODULE or called configure(), you’ll need to call django.setup() to load your settings and populate Django’s application registry. For example:
import django
from django.conf import settings
from myapp import myapp_defaults

settings.configure(default_settings=myapp_defaults, DEBUG=True)
django.setup()

# Now this script or any imported module can use any part of Django it needs.
from myapp import models

我将 DJANGO_SETTINGS_MODULE 设置为配置变量，因此没有将其添加到我的调度程序中。

使用 apscheduler 为 Django 项目在 Procfile (Heroku) 中定义 Cron 作业的问题

ISSUES Defining Cron jobs in Procfile (Heroku) using apscheduler for Django project

python

django

cron

heroku

apscheduler