Drf-yasg: Second request to docs fails with AttributeError

[mkurnikov]

Steps to reproduce:

1. Create django project with manage.py startproject, add "drf_yasg" to INSTALLED_APPS.
2. urls.py:

from django.conf.urls import url
from django.contrib import admin
from drf_yasg import openapi
from drf_yasg.views import get_schema_view
from rest_framework import permissions

urlpatterns = [
    url(r'^admin/', admin.site.urls),
]

schema_view = get_schema_view(
    openapi.Info(
        title="Snippets API",
        default_version='v1'
    ),
    public=True,
    permission_classes=(permissions.AllowAny,)
)

urlpatterns += [
    url(r'swagger/$', schema_view.with_ui('swagger', cache_timeout=None), name='schema-swagger-ui'),
    url(r'redoc/$', schema_view.with_ui('redoc', cache_timeout=None), name='schema-redoc'),
]

1. Start a server with manage.py runserver, first page request correctly shows docs UI, second one fails with AttributeError (trace below)

[15/Dec/2017 11:26:52] "GET /redoc/?format=openapi HTTP/1.1" 200 219
Internal Server Error: /redoc/
Traceback (most recent call last):
  File "/code/mkurnikov/.virtualenvs/project_name/lib/python3.6/site-packages/django/core/handlers/exception.py", line 41, in inner
    response = get_response(request)
  File "/code/mkurnikov/.virtualenvs/project_name/lib/python3.6/site-packages/django/core/handlers/base.py", line 187, in _get_response
    response = self.process_exception_by_middleware(e, request)
  File "/code/mkurnikov/.virtualenvs/project_name/lib/python3.6/site-packages/django/core/handlers/base.py", line 185, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "/code/mkurnikov/.virtualenvs/project_name/lib/python3.6/site-packages/drf_yasg/views.py", line 33, in _wrapped_view_func
    response = view_func(request, *args, **kwargs)
  File "/code/mkurnikov/.virtualenvs/project_name/lib/python3.6/site-packages/django/utils/decorators.py", line 141, in _wrapped_view
    result = middleware.process_request(request)
  File "/code/mkurnikov/.virtualenvs/project_name/lib/python3.6/site-packages/django/middleware/cache.py", line 137, in process_request
    response = self.cache.get(cache_key)
  File "/code/mkurnikov/.virtualenv/sproject_name/lib/python3.6/site-packages/django/core/cache/backends/locmem.py", line 54, in get
    return pickle.loads(pickled)
  File "/code/mkurnikov/.virtualenvs/project_name/lib/python3.6/site-packages/drf_yasg/openapi.py", line 190, in __init__
    self.info.version = _version or info._default_version
AttributeError: 'NoneType' object has no attribute '_default_version'

Django 1.11.7, Python 3.6.3, DRF 3.7.3

[axnsan12]

Huh, this seems to be related to caching. I think I know how I managed to break it, will try to push a fix today.

Workaround for now is to set cache_timeout to 0, I guess...

[mkurnikov]

Ok, thanks a lot.

Project is great by the way, thank you for it.

[axnsan12]

Fixed and pushed to pypi. Can you confirm that it works for you?

[mkurnikov]

Yes, works for me. Thanks!