API root view return nothing when I enable `NamespaceVersioning`

[BrickXu]

Hi guys,

I meet a problem when I enable NamespaceVersioning in the settings. but the APIRoot view return a empty dict in the browsable api page.

here is my settings and code segments:

# In the urls.py
urlpatterns = patterns(
    ......
    url(r"^rest_api", include(router.urls, namespace='v1')),
)

# In the routers.py
router = routers.DefaultRouter()
router.register(r'auth/token', auth_views.TokenViewSet, base_name='token')
router.register(r'auth/groups', auth_views.GroupViewSet, base_name='group')
router.register(r'auth/permissions', auth_views.PermissionViewSet, base_name='permission')
router.register(r'labels', common_views.LabelViewSet, base_name='label')
......

# In the settings.py
REST_FRAMEWORK = {
    ......
    'DEFAULT_VERSIONING_CLASS': 'rest_framework.versioning.NamespaceVersioning',
    'DEFAULT_VERSION': 'v1',
    'ALLOWED_VERSIONS': ['v1'],
}

Then I debug the code, it shows me a very strange view_name in the rest_framework.reverse.reverse, it seems append the version prefix twice, like "v1:v1:label", it caused NoReverseMatch error.

# In the rest_framework/routers.py
class APIRoot(views.APIView):
    _ignore_model_permissions = True

    def get(self, request, *args, **kwargs):
        ret = OrderedDict()
        namespace = get_resolver_match(request).namespace
        for key, url_name in api_root_dict.items():
            if namespace:
                # here append version prefix for the first time.
                url_name = namespace + ':' + url_name
            try:
                ret[key] = reverse(
                    url_name,
                    request=request,
                    format=kwargs.get('format', None)
                )
            except NoReverseMatch:
                continue

        return Response(ret)

# In the rest_framework/reverse.py
def reverse(viewname, args=None, kwargs=None, request=None, format=None, **extra):
    """
    If versioning is being used then we pass any `reverse` calls through
    to the versioning scheme instance, so that the resulting URL
    can be modified if needed.
    """
    scheme = getattr(request, 'versioning_scheme', None)
    if scheme is not None:
        # call NamespaceVersioning.reverse()
        return scheme.reverse(viewname, args, kwargs, request, format, **extra)
    return _reverse(viewname, args, kwargs, request, format, **extra)

# In the rest_framework/versioning.py
def reverse(self, viewname, args=None, kwargs=None, request=None, format=None, **extra):
    if request.version is not None:
        # append version prefix twice!
        viewname = self.get_versioned_viewname(viewname, request)
    return super(NamespaceVersioning, self).reverse(
        viewname, args, kwargs, request, format, **extra
    )

def get_versioned_viewname(self, viewname, request):
    return request.version + ':' + viewname

Do I miss something to set in the settings or I use NamespaceVersioning in the wrong way?

[smcoll]

Same issue. i noticed that the view_name argument in NamespaceVersioning.reverse is already prefixed with 'v1'. That prefixing happens in APIRoot.get() if a namespace is present in the request. @tomchristie perhaps that if namespace: check in APIRoot.get() is not necessary since the reverse is handled by any versioning router anyway? Or is that to provide non-versioning namespace support?