Change the code around rendering mails, maybe yet without a good reas…

…on to

spark/spark_mails/admin.py

@@ -26,8 +26,8 @@ def rendered(self, instance):
         try:
             return format_html(
                 '<div style="white-space:pre-wrap; max-width:40rem">'
-                "<code>{}\n\n{}</code></div>",
-                *instance.render(spark_mails_context(instance)),
+                "<code>{subject}\n\n{body}</code></div>",
+                **instance.render(spark_mails_context(instance)),
             )
         except Exception:
             return format_html('<div style="color:red">INVALID</div>')

spark/spark_mails/api.py

@@ -1,6 +1,6 @@
 import logging
 
-from django.core.mail import EmailMessage
+from django.core.mail import EmailMultiAlternatives
 
 from spark.spark_mails.models import Mail
 
@@ -15,20 +15,15 @@ def process_mail_events(iterable, *, defaults=None, fail_silently=False):
 
 def mails_from_events(iterable, *, defaults=None):
     mails = Mail.objects.as_mails()
+    defaults = {} if defaults is None else defaults
 
     for e in iterable:
         if "spark_mail" not in e["context"]:
             continue
-        kwargs = dict(defaults) if defaults else {}
-        kwargs.update(e["context"]["spark_mail"])
+        kwargs = {**defaults, **e["context"]["spark_mail"]}
         if e["group"] in mails:
             try:
-                subject, body = mails[e["group"]].render(e["context"])
+                kwargs = mails[e["group"]].render(e["context"], **kwargs)
             except Exception:
                 logger.exception("Error while rendering mail subject and body")
-            else:
-                if subject:
-                    kwargs["subject"] = subject
-                if body:
-                    kwargs["body"] = body
-        yield EmailMessage(**kwargs)
+        yield EmailMultiAlternatives(**kwargs)

spark/spark_mails/models.py

@@ -40,7 +40,7 @@ def clean_fields(self, exclude=None):
     def template(self):
         return Template(self.template_source)
 
-    def render(self, context):
+    def render(self, context, **kwargs):
         lines = iter(
             line.rstrip()
             for line in self.template.render(Context(context)).splitlines()
@@ -54,4 +54,7 @@ def render(self, context):
                     break
         except StopIteration:  # if lines is empty
             pass
-        return subject, "\n".join(lines).strip("\n")
+        body = "\n".join(lines).strip("\n")
+        kwargs["subject"] = subject or kwargs.get("subject", "")
+        kwargs["body"] = body or kwargs.get("body", "")
+        return kwargs

tests/testapp/test_mails.py

@@ -30,12 +30,12 @@ def test_mails(self):
 
         stuff = Stuff.objects.create(key="asdf")
 
-        subject, body = m.render(
+        kwargs = m.render(
             {"user": user, "key": stuff.key, "key_length": len(stuff.key)}
         )
 
-        self.assertEqual(subject, "Dear test")
-        self.assertEqual(body, "This is the key: asdf (4)\n\nBest regards")
+        self.assertEqual(kwargs["subject"], "Dear test")
+        self.assertEqual(kwargs["body"], "This is the key: asdf (4)\n\nBest regards")
 
         events = [
             {