Move @has_request_variables error responses to middleware

This will now allow us to use @has_request_variables on helper
functions.

(imported from commit 799d71477654eac7fd8192cfc5bb88b78053532d)

humbug/settings.py

@@ -146,6 +146,7 @@ TEMPLATE_LOADERS = (
 MIDDLEWARE_CLASSES = (
     # Our logging middleware should be the first middleware item.
     'zephyr.middleware.LogRequests',
+    'zephyr.middleware.JsonErrorHandler',
     'django.middleware.common.CommonMiddleware',
     'django.contrib.sessions.middleware.SessionMiddleware',
     'django.middleware.csrf.CsrfViewMiddleware',

zephyr/decorator.py

@@ -118,6 +118,27 @@ def internal_notify_view(view_func):
         return view_func(request, *args, **kwargs)
     return _wrapped_view_func
 
+class RequestVariableMissingError(Exception):
+    def __init__(self, var_name):
+        self.var_name = var_name
+
+    def to_json_error_msg(self):
+        return "Missing '%s' argument" % (self.var_name,)
+
+    def __str__(self):
+        return self.to_json_error_msg()
+
+class RequestVariableConversionError(Exception):
+    def __init__(self, var_name, bad_value):
+        self.var_name = var_name
+        self.bad_value = bad_value
+
+    def to_json_error_msg(self):
+        return "Bad value for '%s': %s" % (self.var_name, self.bad_value)
+
+    def __str__(self):
+        return self.to_json_error_msg()
+
 # Used in conjunction with @has_request_variables, below
 class POST(object):
     # NotSpecified is a sentinel value for determining whether a
@@ -195,7 +216,7 @@ def has_request_variables(view_func):
                 val = request.POST[param.post_var_name]
             except KeyError:
                 if param.default is POST.NotSpecified:
-                    return json_error("Missing '%s' argument" % (param.post_var_name,))
+                    raise RequestVariableMissingError(param.post_var_name)
                 val = param.default
                 default_assigned = True
 
@@ -203,8 +224,7 @@ def has_request_variables(view_func):
                 try:
                     val = param.converter(val)
                 except:
-                    return json_error("Bad value for '%s': %s"
-                                      % (param.post_var_name, val))
+                    raise RequestVariableConversionError(param.post_var_name, val)
             kwargs[param.func_var_name] = val
 
         return view_func(request, *args, **kwargs)

zephyr/middleware.py

@@ -1,3 +1,6 @@
+from decorator import RequestVariableMissingError, RequestVariableConversionError
+from zephyr.lib.response import json_error
+
 import logging
 import time
 
@@ -23,3 +26,9 @@ class LogRequests(object):
             % (remote_ip, request.method, response.status_code,
                time_delta, request.get_full_path()))
         return response
+
+class JsonErrorHandler(object):
+    def process_exception(self, request, exception):
+        if hasattr(exception, 'to_json_error_msg') and callable(exception.to_json_error_msg):
+            return json_error(exception.to_json_error_msg())
+        return None

zephyr/tests.py

@@ -7,7 +7,7 @@ from django.db.models import Q
 from zephyr.models import Message, UserProfile, Stream, Recipient, Subscription, \
     filter_by_subscriptions, get_display_recipient, Realm, do_send_message, Client
 from zephyr.views import json_get_updates, api_get_messages, gather_subscriptions
-from zephyr.decorator import RespondAsynchronously
+from zephyr.decorator import RespondAsynchronously, RequestVariableConversionError
 from zephyr.lib.initial_password import initial_password, initial_api_key
 
 import simplejson
@@ -723,6 +723,17 @@ class GetUpdatesTest(AuthedTestCase):
         request = POSTRequestMock({}, user)
         self.assertEquals(json_get_updates(request), RespondAsynchronously)
 
+    def test_bad_input(self):
+        """
+        Specifying a bad value for 'pointer' should return an error
+        """
+        self.login("hamlet@humbughq.com")
+        user = User.objects.get(email="hamlet@humbughq.com")
+
+        request = POSTRequestMock({'pointer': 'foo'}, user)
+        self.assertRaises(RequestVariableConversionError, json_get_updates, request)
+
+
 class Runner(DjangoTestSuiteRunner):
     option_list = (
         optparse.make_option('--skip-generate',