Improve MandrillAPIError.__str__

* Include formatted response from Mandrill API (if any)
* Clean up recipient address(es)

djrill/exceptions.py

@@ -1,3 +1,4 @@
+import json
 from requests import HTTPError
 import warnings
 
@@ -14,8 +15,15 @@ class MandrillAPIError(HTTPError):
         message = "Mandrill API response %d" % self.status_code
         if self.log_message:
             message += "\n" + self.log_message
-        if self.response:
-            message += "\nResponse: " + getattr(self.response, 'content', "")
+        # Include the Mandrill response, nicely formatted, if possible
+        try:
+            json_response = self.response.json()
+            message += "\nMandrill response:\n" + json.dumps(json_response, indent=2)
+        except (AttributeError, KeyError, ValueError):  # not JSON = ValueError
+            try:
+                message += "\nMandrill response: " + self.response.text
+            except AttributeError:
+                pass
         return message
 
 

djrill/mail/backends/djrill.py

@@ -137,15 +137,16 @@ class DjrillBackend(BaseEmailBackend):
             message.mandrill_response = None
 
             if not self.fail_silently:
-                from_email = msg_dict.get('from_email', None)
-                from_message = ""
-                if from_email:
-                    from_message = ", from %s" % from_email
+                log_message = "Failed to send a message"
+                if 'to' in msg_dict:
+                    log_message += " to " + ','.join(
+                        to['email'] for to in msg_dict.get('to', []) if 'email' in to)
+                if 'from_email' in msg_dict:
+                    log_message += " from %s" % msg_dict['from_email']
                 raise MandrillAPIError(
                     status_code=response.status_code,
                     response=response,
-                    log_message="Failed to send a message to %s%s" %
-                                (msg_dict['to'], from_message))
+                    log_message=log_message)
             return False
 
         # add the response from mandrill to the EmailMessage so callers can inspect it

djrill/tests/test_mandrill_send.py

@@ -308,6 +308,31 @@ class DjrillBackendTests(DjrillBackendMockAPITestCase):
             ['to@example.com'], fail_silently=True)
         self.assertEqual(sent, 0)
 
+    def test_api_error_includes_details(self):
+        """MandrillAPIError should include Mandrill's error message"""
+        msg = mail.EmailMessage('Subject', 'Body', 'from@example.com', ['to@example.com'])
+
+        # JSON error response:
+        error_response = b"""{
+                                 "status": "error",
+                                 "code": 12,
+                                 "name": "Error_Name",
+                                 "message": "Helpful explanation from Mandrill"
+                             }"""
+        self.mock_post.return_value = self.MockResponse(status_code=400, raw=error_response)
+        with self.assertRaisesMessage(MandrillAPIError, "Helpful explanation from Mandrill"):
+            msg.send()
+
+        # Non-JSON error response:
+        self.mock_post.return_value = self.MockResponse(status_code=500, raw=b"Invalid API key")
+        with self.assertRaisesMessage(MandrillAPIError, "Invalid API key"):
+            msg.send()
+
+        # No content in the error response:
+        self.mock_post.return_value = self.MockResponse(status_code=502, raw=None)
+        with self.assertRaises(MandrillAPIError):
+            msg.send()
+
 
 class DjrillMandrillFeatureTests(DjrillBackendMockAPITestCase):
     """Test Djrill backend support for Mandrill-specific features"""

docs/history.rst

@@ -76,6 +76,8 @@ Version 1.4 (development):
   (Specifying a :ref:`Reply-To header <message-headers>`
   still works, with any version of Django,
   and will override the reply_to param if you use both.)
+* Include Mandrill error response in str(MandrillAPIError),
+  to make errors easier to understand.
 * More-helpful exception when using a non-JSON-serializable
   type in merge_vars and other Djrill message attributes
 * Deprecation warnings for upcoming 2.0 changes (see above)