Allow global_merge_vars to be merged in with the per message dict, with keys in the latter taking precedent.

Update the docs accordingly.

AUTHORS.txt

@@ -17,3 +17,4 @@ Sameer Al-Sakran
 Kyle Gibson
 Wes Winham
 nikolay-saskovets
+William Hector

djrill/mail/backends/djrill.py

@@ -285,12 +285,17 @@ class DjrillBackend(BaseEmailBackend):
 
         # Allow simple python dicts in place of Mandrill
         # [{name:name, value:value},...] arrays...
+
+        # Allow merge of global and per message global_merge_var, the former taking precedent
+        global_merge_vars = {}
         if 'global_merge_vars' in self.global_settings:
-            msg_dict['global_merge_vars'] = self._expand_merge_vars(
+            global_merge_vars.update(self.global_settings['global_merge_vars'])
-                self.global_settings['global_merge_vars'])
         if hasattr(message, 'global_merge_vars'):
+            global_merge_vars.update(message.global_merge_vars)
+        if global_merge_vars:
             msg_dict['global_merge_vars'] = \
-                self._expand_merge_vars(message.global_merge_vars)
+                self._expand_merge_vars(global_merge_vars)
+
         if hasattr(message, 'merge_vars'):
             # For testing reproducibility, we sort the recipients
             msg_dict['merge_vars'] = [

djrill/tests/test_mandrill_send.py

@@ -650,11 +650,21 @@ class DjrillMandrillGlobalFeatureTests(DjrillBackendMockAPITestCase):
         self.assertEqual(data['message']['url_strip_qs'], False)
 
     def test_global_merge(self):
+        # Test that global settings merge in
         self.message.global_merge_vars = {'GREETING': "Hello"}
         self.message.send()
         data = self.get_api_call_data()
         self.assertEqual(data['message']['global_merge_vars'],
-                         [{'name': "GREETING", 'content': "Hello"}])
+                         [{'name': "GREETING", 'content': "Hello"},
+                          {'name': 'TEST', 'content': 'djrill'}])
+
+    def test_global_merge_overwrite(self):
+        # Test that global merge settings are overwritten
+        self.message.global_merge_vars = {'TEST': "Hello"}
+        self.message.send()
+        data = self.get_api_call_data()
+        self.assertEqual(data['message']['global_merge_vars'],
+                         [{'name': 'TEST', 'content': 'Hello'}])
 
 
 @override_settings(EMAIL_BACKEND="djrill.mail.backends.djrill.DjrillBackend")

docs/usage/sending_mail.rst

@@ -118,6 +118,10 @@ using :setting:`MANDRILL_SETTINGS`. For Example::
         'track_opens': True,
     }
 
+.. note::
+    ``merge_vars`` and ``recipient_metadata`` cannot be set globally. ``global_merge_vars`` is merged
+    (see :attribute:`global_merge_vars`)
+
 .. These attributes are in the same order as they appear in the Mandrill API docs...
 
 .. attribute:: important
@@ -211,6 +215,10 @@ using :setting:`MANDRILL_SETTINGS`. For Example::
     Merge data must be strings or other JSON-serializable types.
     (See :ref:`formatting-merge-data` for details.)
 
+        .. note::
+
+        If using :setting:`MANDRILL_SETTINGS` then the message ``dict`` will be merged and overwrite any duplicates.
+
 .. attribute:: merge_vars
 
     ``dict``: per-recipient merge variables (most useful with :ref:`mandrill-templates`). The keys