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pythondjangoif-statementhttp-referer

Python - if, elif, elif, else Statement Not Working as Expected

I'm using Django for a web site and needed to build a context processor to provide referrer (variable named referer) information.

I have a simple if, elif, elif, else statement:

[ . . . ]

host = get_current_site(request)
local_url = SITE_URLS['local']
dev_url = SITE_URLS['dev']
prod_url = SITE_URLS['prod']

# print referer for debugging purposes - remove when done...
print("current host: {0}".format(host))
print("current urls: {0} {1} {2}".format(local_url, dev_url, prod_url))

# determine default referer - eg, set as host/site name
if host == prod_url:
    referer = prod_url

elif host == dev_url:
    referer = dev_url

elif host == local_url:
    referer = local_url

else:
    # set referer for current request
    try:
        referer = request.META['HTTP_REFERER']

    except KeyError as e:
        print('ERROR: key error - referer doesn\'t exist: {0}'.format(str(e)));

[ . . . ]

What's weird is that the print statements above yield the host being equal to the local_url (from console):

current host: http://localhost:8000
current urls: http://localhost:8000 [ . . . ]

Yet it is still evaluating the else > try and throwing a key error... The point is that only when the default host/site is not available, then the request.META['HTTP_REFERER'] is valid.

What is going wrong here? I'm missing something. Python is telling me that host != local_url but why?

EDIT

Thanks to a great hint from @Martijn Pieters. I changed the print statements and now see this:

current host: <Site: http://localhost:8000>
current urls: 'http://localhost:8000'

I think I forgot to use the attributes for the sites framework:

https://docs.djangoproject.com/en/dev/ref/contrib/sites/

Solution

  • Most likely you have a whitespace issue; replace your formatting with:

    print("current host: {0!r}".format(host))
print("current urls: {0!r} {1!r} {2!r}".format(local_url, dev_url, prod_url))

    to use repr() values instead; these will include more information on the type of the value and any trailing whitespace will be immediately obvious.

    If you see a django.contrib.sites.models.Site object, compare against the domain attribute:

    if host.domain == prod_url: