Fix #61: Handle text/* attachments passed as a text-string

.gitignore

@@ -83,6 +83,10 @@ celerybeat-schedule
 # dotenv
 .env
 
+# direnv
+.direnv/
+.envrc
+
 # virtualenv
 venv/
 ENV/

sgbackend/mail.py

@@ -128,21 +128,42 @@ def _build_sg_mail(self, email):
                 mail.set_reply_to(Email(reply_to_email))
 
         for attachment in email.attachments:
+            filename, content, mimetype = (None, None, None)
             if isinstance(attachment, MIMEBase):
-                attach = Attachment()
-                attach.set_filename(attachment.get_filename())
-                attach.set_content(base64.b64encode(attachment.get_payload()))
-                mail.add_attachment(attach)
-            elif isinstance(attachment, tuple):
-                attach = Attachment()
-                attach.set_filename(attachment[0])
-                base64_attachment = base64.b64encode(attachment[1])
-                if sys.version_info >= (3,):
-                    attach.set_content(str(base64_attachment, 'utf-8'))
+                # If the attachment is a MIMEBase instance
+                filename = attachment.get_filename()
+                content = attachment.get_payload()
+                mimetype = attachment.get_content_type()
+                if attachment.get_content_maintype() == 'text' \
+                    and isinstance(content, str):
+                    content = base64.b64encode(
+                        content.encode('utf-8')).decode('utf-8')
                 else:
-                    attach.set_content(base64_attachment)
-                attach.set_type(attachment[2])
-                mail.add_attachment(attach)
+                    content = base64.b64encode(content).decode('utf-8')
+
+            elif isinstance(attachment, tuple):
+                filename, content, mimetype = attachment
+                basetype, subtype = mimetype.split('/', 1)
+
+                if basetype == 'text' and isinstance(content, str):
+                    # Django expects a text string if the MIME type is 
+                    # text/*, so we'll need to encode the string
+                    content = base64.b64encode(
+                        content.encode('utf-8')).decode('utf-8')
+
+                if isinstance(content, bytes):
+                    # If the content is bytes, simply encode then convert
+                    # to a text string
+                    content = base64.b64encode(content).decode('utf-8')
+
+            assert content is not None
+
+            attach = Attachment()
+            attach.set_filename(filename)
+            attach.set_content(content)
+            attach.set_type(mimetype)
+
+            mail.add_attachment(attach)
 
         mail.add_personalization(personalization)
         return mail.get()

tests/test_mail.py

@@ -1,3 +1,5 @@
+from email.mime.text import MIMEText
+
 from django.conf import settings
 from django.core.exceptions import ImproperlyConfigured
 from django.core.mail import EmailMessage
@@ -182,3 +184,80 @@ def test_build_sg_email_w_extra_headers(self):
                  'personalizations': [{'subject': ''}],
                  'subject': ''}
             )
+
+    def test_build_sg_email_w_string_attachment(self):
+        """
+        Test text/* attachment passed as a text string
+        """
+        attachments = (('file.txt', 'String content', 'text/plain'),)
+        msg = EmailMessage(attachments=attachments)
+        with self.settings(SENDGRID_API_KEY='test_key'):
+            mail = SendGridBackend()._build_sg_mail(msg)
+            self.assertEqual(
+                mail,
+                {'from': {'email': 'webmaster@localhost'},
+                 'subject': '', 'personalizations': [{'subject': ''}],
+                 'content': [{'type': 'text/plain', 'value': ''}],
+                 'attachments': [{
+                    'content': 'U3RyaW5nIGNvbnRlbnQ=',
+                    'type': 'text/plain',
+                    'filename': 'file.txt'}]}
+            )
+
+    def test_build_sg_email_w_binary_attachment(self):
+        """
+        Test text attachment passed as binary
+        """
+        attachments = (('file.txt', b'Binary content', 'text/plain'),)
+        msg = EmailMessage(attachments=attachments)
+        with self.settings(SENDGRID_API_KEY='test_key'):
+            mail = SendGridBackend()._build_sg_mail(msg)
+            self.assertEqual(
+                mail,
+                {'from': {'email': 'webmaster@localhost'},
+                 'subject': '', 'personalizations': [{'subject': ''}],
+                 'content': [{'type': 'text/plain', 'value': ''}],
+                 'attachments': [{
+                    'content': 'QmluYXJ5IGNvbnRlbnQ=',
+                    'type': 'text/plain',
+                    'filename': 'file.txt'}]}
+            )
+
+    def test_build_sg_email_w_image_attachment(self):
+        """
+        Test image attachment
+        """
+        with open('tests/assets/test-image.png', 'rb') as f:
+            content = f.read()
+        attachments = (('file.png', content, 'image/png'),)
+        msg = EmailMessage(attachments=attachments)
+        with self.settings(SENDGRID_API_KEY='test_key'):
+            mail = SendGridBackend()._build_sg_mail(msg)
+            self.assertEqual(
+                mail,
+                {'from': {'email': 'webmaster@localhost'},
+                 'subject': '', 'personalizations': [{'subject': ''}],
+                 'content': [{'type': 'text/plain', 'value': ''}],
+                 'attachments': [{
+                    'content': 'iVBORw0KGgoAAAANSUhEUgAAABAAAAAQCAYAAAAf8/9hAAAA8ElEQVR42o2TQQqCQBiFhdq5alFt3YbgBYICD+JB7AJ1AEFaiKtAOkRQ64iWgpjrVtU21P4f/oGHjDkDH/i/ee8xM6DVXfPpzCUSoiRqoRTNRa8unBHtAFlfOGeDIXk3fJSNOxEQD5lfQitaIJ6WMyrsQfPeGljsAb/HQgpCYlCQgD9loQLBNiiwwV+x0MjwtQwXeyXT8FCrRtMCOEHNQwGCbxD2wV+wEMM1PoTzJ+wQbyiIlcjDhjjI95VYQnBF3GQPcZQhYgH+gxMxgoKxJhx1j3cmnsSaWOgeDrj03XGrTH8KdkOvPCFCjR7yXlf/AfSXkoJCC4ZeAAAAAElFTkSuQmCC',
+                    'type': 'image/png',
+                    'filename': 'file.png'}]}
+            )
+
+    def test_build_sg_email_w_mimebase_attachment(self):
+        """
+        Test MIMEBase attachment
+        """
+        attachments = (MIMEText('Mime text', 'plain'), )
+        msg = EmailMessage(attachments=attachments)
+        with self.settings(SENDGRID_API_KEY='test_key'):
+            mail = SendGridBackend()._build_sg_mail(msg)
+            self.assertEqual(
+                mail,
+                {'from': {'email': 'webmaster@localhost'},
+                'subject': '', 'personalizations': [{'subject': ''}],
+                'content': [{'type': 'text/plain', 'value': ''}], 
+                'attachments': [{
+                    'content': 'TWltZSB0ZXh0',
+                    'type': 'text/plain'}]}
+            )