From 5d417080eef983ed8bcc2c158673f431531df725 Mon Sep 17 00:00:00 2001
From: medmunds <medmunds@gmail.com>
Date: Wed, 1 Jun 2016 08:05:51 -0700
Subject: [PATCH] SendGrid: set `to` to `from` in batch send.

Set ignored (but required-valid) `to` field to
the from_email for batch send with merge_data.
See https://github.com/anymail/django-anymail/pull/14#issuecomment-220231250
---
 anymail/backends/sendgrid.py   | 9 +++++++--
 tests/test_sendgrid_backend.py | 9 ++++++---
 2 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/anymail/backends/sendgrid.py b/anymail/backends/sendgrid.py
index 9bf2232..b7e6f44 100644
--- a/anymail/backends/sendgrid.py
+++ b/anymail/backends/sendgrid.py
@@ -96,9 +96,14 @@ class SendGridPayload(RequestsPayload):
 
         self.build_merge_data()
         if self.merge_data is not None:
-            # Must *also* set smtpapi 'to' field so SG does batch send
-            # (else all recipients would see each other's emails)
+            # Move the 'to' recipients to smtpapi, so SG does batch send
+            # (else all recipients would see each other's emails).
+            # Regular 'to' must still be a valid email (even though "ignored")...
+            # we use the from_email as recommended by SG support
+            # (See https://github.com/anymail/django-anymail/pull/14#issuecomment-220231250)
             self.smtpapi['to'] = [email.address for email in self.to_list]
+            self.data['to'] = [self.data['from']]
+            self.data['toname'] = [self.data.get('fromname', " ")]
 
         # Serialize x-smtpapi to json:
         if len(self.smtpapi) > 0:
diff --git a/tests/test_sendgrid_backend.py b/tests/test_sendgrid_backend.py
index 23e1ef2..a9e5fe7 100644
--- a/tests/test_sendgrid_backend.py
+++ b/tests/test_sendgrid_backend.py
@@ -413,6 +413,7 @@ class SendGridBackendAnymailFeatureTests(SendGridBackendMockAPITestCase):
         })
 
     def test_merge_data(self):
+        self.message.from_email = 'from@example.com'
         self.message.to = ['alice@example.com', 'Bob <bob@example.com>']
         # SendGrid template_id is not required to use merge.
         # You can just supply template content as the message (e.g.):
@@ -431,10 +432,12 @@ class SendGridBackendAnymailFeatureTests(SendGridBackendMockAPITestCase):
 
         data = self.get_api_call_data()
         smtpapi = self.get_smtpapi()
-        # For batch send, must set both to+toname *and* smtpapi['to']:
-        self.assertEqual(data['toname'], [' ', 'Bob'])
-        self.assertEqual(data['to'], ['alice@example.com', 'bob@example.com'])
+        # For batch send, smtpapi['to'] gets real recipient list;
+        # normal 'to' is not used (but must be valid, so we substitute the from_email):
+        self.assertEqual(data['to'], ['from@example.com'])
+        self.assertEqual(data['toname'], [' '])  # empty string if no name in from_email
         self.assertEqual(smtpapi['to'], ['alice@example.com', 'Bob <bob@example.com>'])
+        # smtpapi['sub'] values should be in to-list order:
         self.assertEqual(smtpapi['sub'], {
             ':name': ["Alice", "Bob"],
             ':group': ["Developers", ":group"],  # missing value gets replaced with var name...