Update default error pages.

awx/main/views.py

@@ -3,33 +3,67 @@
 
 # Django
 from django.shortcuts import render
-from django.utils.safestring import mark_safe
+from django.utils.html import format_html
+
+# Django REST Framework
+from rest_framework import exceptions, permissions, views
+
+
+class ApiErrorView(views.APIView):
+
+    authentication_classes = []
+    permission_classes = (permissions.AllowAny,)
+    metadata_class = None
+    allowed_methods = ('GET', 'HEAD')
+    exception_class = exceptions.APIException
+    view_name = 'API Error'
+
+    def get_view_name(self):
+        return self.view_name
+
+    def get(self, request, format=None):
+        raise self.exception_class()
+
 
 def handle_error(request, status=404, **kwargs):
-    # FIXME: Should attempt to check HTTP Accept request header and return
-    # plain JSON response instead of HTML (maybe only for /api/*).
-    context = kwargs
-    # Return enough context to popuplate the base API template.
-    description = u'<pre class="err">%s</pre>' % context.get('content', '')
-    context['description'] = mark_safe(description)
-    context['content'] = ''
-    template_name = 'error.html'
-    return render(request, template_name, context, status=status)
+    # For errors to /api/*, use a simple DRF view/exception to generate a
+    # browsable error page for browser clients or a simple JSON response for any
+    # other clients.
+    if request.path.startswith('/api/'):
+        class APIException(exceptions.APIException):
+            status_code = status
+            default_detail = kwargs['content']
+        api_error_view = ApiErrorView.as_view(view_name=kwargs['name'], exception_class=APIException)
+        return api_error_view(request)
+    else:
+        kwargs['content'] = format_html('<span class="nocode">{}</span>', kwargs.get('content', ''))
+        return render(request, 'error.html', kwargs, status=status)
+
+
+def handle_400(request):
+    kwargs = {
+        'name': 'Bad Request',
+        'content': 'The request could not be understood by the server.',
+    }
+    return handle_error(request, 400, **kwargs)
+
 
 def handle_403(request):
     kwargs = {
         'name': 'Forbidden',
-        'content': 'You don\'t have permission to access the requested page.',
+        'content': 'You don\'t have permission to access the requested resource.',
     }
     return handle_error(request, 403, **kwargs)
 
+
 def handle_404(request):
     kwargs = {
         'name': 'Not Found',
-        'content': 'The requested page could not be found.',
+        'content': 'The requested resource could not be found.',
     }
     return handle_error(request, 404, **kwargs)
 
+
 def handle_500(request):
     kwargs = {
         'name': 'Server Error',