NoReverseMatch - 「viewflow」是不是已註冊的命名空間

Question

當試圖從官方cookbook爲viewflow運行自定義UI應用程序（「包裹」）我得到這個錯誤：

NoReverseMatch at /parcel/delivery/5/start/21/detail/ 'viewflow' is not a registered namespace

我參加了一個截圖：

這裏的回溯：

Environment: 


Request Method: GET 
Request URL: http://localhost:8000/parcel/delivery/5/start/21/detail/ 

Django Version: 1.10.7 
Python Version: 3.4.0 
Installed Applications: 
['django.contrib.admin', 
'django.contrib.auth', 
'django.contrib.contenttypes', 
'django.contrib.sessions', 
'django.contrib.messages', 
'django.contrib.staticfiles', 
'material', 
'material.frontend', 
'viewflow', 
'viewflow.frontend', 
'apps.parcel'] 
Installed Middleware: 
['django.middleware.security.SecurityMiddleware', 
'django.contrib.sessions.middleware.SessionMiddleware', 
'django.middleware.common.CommonMiddleware', 
'django.middleware.csrf.CsrfViewMiddleware', 
'django.contrib.auth.middleware.AuthenticationMiddleware', 
'django.contrib.messages.middleware.MessageMiddleware', 
'django.middleware.clickjacking.XFrameOptionsMiddleware'] 


Template error: 
In template /Users/paul/delete-viewflows/templates/parcel/delivery/task_detail.html, error at line 0 
    'viewflow' is not a registered namespace 1 : {% extends 'viewflow/flow/base_task.html' %} 
    2 : {% load viewflow %} 
    3 : 
    4 : {% block nav_parcels_cls %}class="active"{% endblock %} 
    5 : 
    6 : {% block task_actions %} 
    7 : {% flowurl activation.task 'execute' user=request.user as execute_url %} 
    8 : {% if execute_url %} 
    9 : <a href="{{ execute_url }}" class="btn primary">Execute</a> 
    10 : {% endif %} 


Traceback: 

File "/Users/paul/.pyenv/versions/dj-viewflow/lib/python3.4/site-packages/django/urls/base.py" in reverse 
    77.     extra, resolver = resolver.namespace_dict[ns] 

During handling of the above exception ('viewflow'), another exception occurred: 

File "/Users/paul/.pyenv/versions/dj-viewflow/lib/python3.4/site-packages/django/core/handlers/exception.py" in inner 
    42.    response = get_response(request) 

File "/Users/paul/.pyenv/versions/dj-viewflow/lib/python3.4/site-packages/django/core/handlers/base.py" in _get_response 
    217.     response = self.process_exception_by_middleware(e, request) 

File "/Users/paul/.pyenv/versions/dj-viewflow/lib/python3.4/site-packages/django/core/handlers/base.py" in _get_response 
    215.     response = response.render() 

File "/Users/paul/.pyenv/versions/dj-viewflow/lib/python3.4/site-packages/django/template/response.py" in render 
    109.    self.content = self.rendered_content 

File "/Users/paul/.pyenv/versions/dj-viewflow/lib/python3.4/site-packages/django/template/response.py" in rendered_content 
    86.   content = template.render(context, self._request) 

File "/Users/paul/.pyenv/versions/dj-viewflow/lib/python3.4/site-packages/django/template/backends/django.py" in render 
    66.    return self.template.render(context) 

File "/Users/paul/.pyenv/versions/dj-viewflow/lib/python3.4/site-packages/django/template/base.py" in render 
    208.      return self._render(context) 

File "/Users/paul/.pyenv/versions/dj-viewflow/lib/python3.4/site-packages/django/template/base.py" in _render 
    199.   return self.nodelist.render(context) 

File "/Users/paul/.pyenv/versions/dj-viewflow/lib/python3.4/site-packages/django/template/base.py" in render 
    994.     bit = node.render_annotated(context) 

File "/Users/paul/.pyenv/versions/dj-viewflow/lib/python3.4/site-packages/django/template/base.py" in render_annotated 
    961.    return self.render(context) 

File "/Users/paul/.pyenv/versions/dj-viewflow/lib/python3.4/site-packages/django/template/loader_tags.py" in render 
    174.   return compiled_parent._render(context) 

File "/Users/paul/.pyenv/versions/dj-viewflow/lib/python3.4/site-packages/django/template/base.py" in _render 
    199.   return self.nodelist.render(context) 

File "/Users/paul/.pyenv/versions/dj-viewflow/lib/python3.4/site-packages/django/template/base.py" in render 
    994.     bit = node.render_annotated(context) 

File "/Users/paul/.pyenv/versions/dj-viewflow/lib/python3.4/site-packages/django/template/base.py" in render_annotated 
    961.    return self.render(context) 

File "/Users/paul/.pyenv/versions/dj-viewflow/lib/python3.4/site-packages/django/template/loader_tags.py" in render 
    174.   return compiled_parent._render(context) 

File "/Users/paul/.pyenv/versions/dj-viewflow/lib/python3.4/site-packages/django/template/base.py" in _render 
    199.   return self.nodelist.render(context) 

File "/Users/paul/.pyenv/versions/dj-viewflow/lib/python3.4/site-packages/django/template/base.py" in render 
    994.     bit = node.render_annotated(context) 

File "/Users/paul/.pyenv/versions/dj-viewflow/lib/python3.4/site-packages/django/template/base.py" in render_annotated 
    961.    return self.render(context) 

File "/Users/paul/.pyenv/versions/dj-viewflow/lib/python3.4/site-packages/django/template/loader_tags.py" in render 
    174.   return compiled_parent._render(context) 

File "/Users/paul/.pyenv/versions/dj-viewflow/lib/python3.4/site-packages/django/template/base.py" in _render 
    199.   return self.nodelist.render(context) 

File "/Users/paul/.pyenv/versions/dj-viewflow/lib/python3.4/site-packages/django/template/base.py" in render 
    994.     bit = node.render_annotated(context) 

File "/Users/paul/.pyenv/versions/dj-viewflow/lib/python3.4/site-packages/django/template/base.py" in render_annotated 
    961.    return self.render(context) 

File "/Users/paul/.pyenv/versions/dj-viewflow/lib/python3.4/site-packages/django/template/loader_tags.py" in render 
    174.   return compiled_parent._render(context) 

File "/Users/paul/.pyenv/versions/dj-viewflow/lib/python3.4/site-packages/django/template/base.py" in _render 
    199.   return self.nodelist.render(context) 

File "/Users/paul/.pyenv/versions/dj-viewflow/lib/python3.4/site-packages/django/template/base.py" in render 
    994.     bit = node.render_annotated(context) 

File "/Users/paul/.pyenv/versions/dj-viewflow/lib/python3.4/site-packages/django/template/base.py" in render_annotated 
    961.    return self.render(context) 

File "/Users/paul/.pyenv/versions/dj-viewflow/lib/python3.4/site-packages/django/template/loader_tags.py" in render 
    174.   return compiled_parent._render(context) 

File "/Users/paul/.pyenv/versions/dj-viewflow/lib/python3.4/site-packages/django/template/base.py" in _render 
    199.   return self.nodelist.render(context) 

File "/Users/paul/.pyenv/versions/dj-viewflow/lib/python3.4/site-packages/django/template/base.py" in render 
    994.     bit = node.render_annotated(context) 

File "/Users/paul/.pyenv/versions/dj-viewflow/lib/python3.4/site-packages/django/template/base.py" in render_annotated 
    961.    return self.render(context) 

File "/Users/paul/.pyenv/versions/dj-viewflow/lib/python3.4/site-packages/django/template/loader_tags.py" in render 
    70.     result = block.nodelist.render(context) 

File "/Users/paul/.pyenv/versions/dj-viewflow/lib/python3.4/site-packages/django/template/base.py" in render 
    994.     bit = node.render_annotated(context) 

File "/Users/paul/.pyenv/versions/dj-viewflow/lib/python3.4/site-packages/django/template/base.py" in render_annotated 
    961.    return self.render(context) 

File "/Users/paul/.pyenv/versions/dj-viewflow/lib/python3.4/site-packages/django/template/loader_tags.py" in render 
    70.     result = block.nodelist.render(context) 

File "/Users/paul/.pyenv/versions/dj-viewflow/lib/python3.4/site-packages/django/template/base.py" in render 
    994.     bit = node.render_annotated(context) 

File "/Users/paul/.pyenv/versions/dj-viewflow/lib/python3.4/site-packages/django/template/base.py" in render_annotated 
    961.    return self.render(context) 

File "/Users/paul/.pyenv/versions/dj-viewflow/lib/python3.4/site-packages/django/template/loader_tags.py" in render 
    70.     result = block.nodelist.render(context) 

File "/Users/paul/.pyenv/versions/dj-viewflow/lib/python3.4/site-packages/django/template/base.py" in render 
    994.     bit = node.render_annotated(context) 

File "/Users/paul/.pyenv/versions/dj-viewflow/lib/python3.4/site-packages/django/template/base.py" in render_annotated 
    961.    return self.render(context) 

File "/Users/paul/.pyenv/versions/dj-viewflow/lib/python3.4/site-packages/django/template/defaulttags.py" in render 
    209.      nodelist.append(node.render_annotated(context)) 

File "/Users/paul/.pyenv/versions/dj-viewflow/lib/python3.4/site-packages/django/template/base.py" in render_annotated 
    961.    return self.render(context) 

File "/Users/paul/.pyenv/versions/dj-viewflow/lib/python3.4/site-packages/django/template/defaulttags.py" in render 
    315.     return nodelist.render(context) 

File "/Users/paul/.pyenv/versions/dj-viewflow/lib/python3.4/site-packages/django/template/base.py" in render 
    994.     bit = node.render_annotated(context) 

File "/Users/paul/.pyenv/versions/dj-viewflow/lib/python3.4/site-packages/django/template/base.py" in render_annotated 
    961.    return self.render(context) 

File "/Users/paul/.pyenv/versions/dj-viewflow/lib/python3.4/site-packages/django/template/base.py" in render 
    1044.    output = self.filter_expression.resolve(context) 

File "/Users/paul/.pyenv/versions/dj-viewflow/lib/python3.4/site-packages/django/template/base.py" in resolve 
    711.     obj = self.var.resolve(context) 

File "/Users/paul/.pyenv/versions/dj-viewflow/lib/python3.4/site-packages/django/template/base.py" in resolve 
    852.    value = self._resolve_lookup(context) 

File "/Users/paul/.pyenv/versions/dj-viewflow/lib/python3.4/site-packages/django/template/base.py" in _resolve_lookup 
    915.        current = current() 

File "/Users/paul/.pyenv/versions/dj-viewflow/lib/python3.4/site-packages/viewflow/frontend/apps.py" in index_url 
    55.   return reverse('viewflow:index') 

File "/Users/paul/.pyenv/versions/dj-viewflow/lib/python3.4/site-packages/django/urls/base.py" in reverse 
    87.      raise NoReverseMatch("%s is not a registered namespace" % key) 

Exception Type: NoReverseMatch at /parcel/delivery/5/start/21/detail/ 
Exception Value: 'viewflow' is not a registered namespace 

我試圖尋找在viewfl的urls.py要包括在我的項目中，但找不到任何東西。

我該如何解決這個問題？

Answer 1

UPDATE：請參閱下面的註釋以獲取實際的正確答案。

問題是我錯過了frontend_urls到我的項目urls.py。示例代碼中缺少了這一點。 這裏是工作urls.py：

from django.contrib import admin 
from django.conf.urls import include, url 
from django.views import generic 
from material.frontend import urls as frontend_urls 

urlpatterns = [ 
    url(r'^admin/', admin.site.urls), 
    url('^$', generic.TemplateView.as_view(template_name='parcel/index.html')), 
    url('^parcel/', include('apps.parcel.urls', namespace='parcel')), 
    url('^accounts/', include('django.contrib.auth.urls')), 
    url(r'', include(frontend_urls)), 
]