Read static file in view - django

Question

To integrate Django and Ember, I have decided to serve my Ember SPA in a Django view (avoids CORS issues, only one server for frontend and API, etc). I do it like this:
# urls.py
urlpatterns = [
url(r'^admin/', include(admin.site.urls)),
url(r'^api/', include(api_urls, namespace='api')),
...
url(r'^$', views.emberapp, name='emberapp'),
...
]
# views.py
from django.http import HttpResponse
def emberapp(request):
# The Ember frontend SPA index file
# This only works in development, and is anyway hacky
EMBER_FE_INDEX_HTML = '/absolute/path/to/my/frontend/static/fe-dist/index.html'
template_file = open(EMBER_FE_INDEX_HTML)
html_content = index_file.read()
index_file.close()
return HttpResponse(html_content)
The index.html is part of the static assets. In development this is very easy:
The index.html is directly accessible to the Django application in the file system
I know the absolute path to the index file
But in production things are more complex, because the static assets are not local to the django application, but accessible on Amazon S3. I use django-storages for that.
How can I read the contents of a static file from a view, in a generic way, no matter what backend is used to store/serve the static files?

Answer 1

First, I don't think the way you do it is a good idea.
But, to answer your question: In your settings.py, you likely have defined the directory where Django will collect all static files.
BASE_DIR = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
STATIC_ROOT = os.path.join(BASE_DIR, 'static')
So in your view, you just need to fetch the file os.path.join(settings.STATIC_ROOT, 'index.html')
That said, you should serve index.html via the webserver, same as your static/ files, robots.txt, favicon.ico, etc. Not through Django. The webserver is much faster, uses proper caching, and its just one line in your Nginx or Apache settings, instead of an entire view function in Django.

Answer 2

This is my current solution. Works in development, not sure about production yet (it is a pain that you need to commit untested code to verify production-related code in Heroku)
from django.conf import settings
from django.http import HttpResponse
from django.core.files.storage import get_storage_class
FE_INDEX_HTML = 'fe/index.html' # relative to the collectstatic directory
def emberapp(request):
# The Ember frontend SPA index file
# By getting the storage_class like this, we guarantee that this will work
# no matter what backend is used for serving static files
# Which means, this will work both in development and production
# Make sure to run collectstatic (even in development)
# TODO: how to use this in development without being forced to run collectstatic?
storage_class = get_storage_class(settings.STATICFILES_STORAGE)
# TODO: reading from a storage backend can be slow if assets are in a third-party server (like Amazon S3)
# Maybe streaming the static file from the server would be faster?
# No redirect to the Amazon S3 asset, please, since the Ember App needs to
# run from the same URL as the API, otherwise you get CORS issues
with storage_class().open(FE_VWORKS_INDEX_HTML) as index_file:
html_content = index_file.read()
return HttpResponse(html_content)
Or, to reply with an StreamingHttpResponse, which does not force Django to read the whole file in memory (and wait for it to be read):
def emberapp(request):
# The Ember frontend SPA index file
# By getting the storage_class like this, we guarantee that this will work
# no matter what backend is used for serving static files
# Which means, this will work both in development and production
# Make sure to run collectstatic (even in development)
# TODO: how to use this in development without being forced to run collectstatic?
storage_class = get_storage_class(settings.STATICFILES_STORAGE)
index_file = storage_class().open(FE_INDEX_HTML)
return StreamingHttpResponse(index_file)