urls.py在Heroku中引发ImportError但在本地不引发

Question

I'm relatively new to django and the Heroku environment and I suspect I'm having the following issue because of something small I've neglected in my project. Basically I'm able to manage.py runserver locally without any issues, and local http views are displayed as expected. I'm able to push changes to Heroku without error as well.

However, when I try to access my remote Heroku project via http, I get an ImportError from the app's urls.py . I believe the pycup app is defined properly in the project's settings.py , since it is able to run locally. Nevertheless I've tried importing 'apps.pycup' and simply 'apps' to settings without success.

My original thought was that somehow Heroku wasn't reading the file structure properly, or maybe git wasn't pushing the __init__.py file inside the apps folder to Heroku but after doing a quick check with heroku run bash and ls apps/ it's clear that's not the case.

The reason I'm using an apps/ folder to contain the pycup app was that it was suggested on a how-to blog and it seemed like a good suggestion for potential future scalability to neatly develop more apps in the project.

Here is the basic file structure I'm using:

manage.py
Procfile
requirements.txt
reunion
|___ static
|___ settings.py
|___ urls.py
|___ wsgi.py
|___ __init__.py
|___ __pycache__.py
apps
|___ pycup
| |___ admin.py
| |___ apps.py
| |___ migrations
| |___ models.py
| |___ static
| |___ templates
| |___ tests.py
| |___ urls.py
| |___ views.py
| |___ __init__.py
| |___ __pycache__.py
|___ __init__.py
|___ __pycache__.py

Below are code samples from both urls.py files in the project:

from the main project folder reunion/urls.py :

from django.conf.urls import include, url
from django.contrib import admin

from apps.pycup import urls as pycupurls

urlpatterns = [
    # Examples:
    # url(r'^$', 'reunion.views.home', name='home'),
    # url(r'^blog/', include('blog.urls')),

    url(r'^admin/', include(admin.site.urls)),
    url(r'^', include(pycupurls)),
]

from the app folder apps/pycup/urls.py :

from django.conf.urls import include, url
from django.contrib import admin

from apps.pycup import views # <- This is the line to which the error is traced in Heroku

urlpatterns = [
    # Examples:
    # url(r'^blog/', include('blog.urls')),
    # url(r'^admin/', include(admin.site.urls)),

    url(r'^$', views.index, name='index'),
]

And this is the error I get:

ImportError at /
No module named pycup
Request Method: GET
Request URL:    http://********.herokuapp.com/
Django Version: 1.9.2
Exception Type: ImportError
Exception Value: No module named pycup
Exception Location: /app/apps/pycup/urls.py in <module>, line 4
Python Executable:  /app/.heroku/python/bin/python
Python Version: 2.7.11

Answer 1

If you are in the same parent folder as the item you are trying to import, you do not put the root path to the item you are calling. So where you have "from apps.pycup import views" it only needs to be "from . import views". What your code is actually doing with the statement you have is attempting to access the "apps.py" file under the parent pycup folder and it is not finding a function in that folder called pycup