feat: add EmailTemplate versioning

Author: Lukáš Klíma

docs/installation.rst

@@ -130,7 +130,7 @@ E-MAIL
 
 .. attribute:: PYMESS_EMAIL_TEMPLATE_BASE_TEMPLATE
 
-  Path to the file containing an e-mail content in the Django template system format.
+  Path to the file containing e-mail content in Django template format. For multiple template versions, define them as a dictionary: ``{"version": "path"}``.
 
 .. attribute:: PYMESS_EMAIL_TEMPLATE_TEMPLATETAGS
 

pymess/migrations/0033_migration.py

@@ -0,0 +1,18 @@
+# Generated by Django 4.2.23 on 2025-08-06 10:19
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('pymess', '0032_migration'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='emailtemplate',
+            name='version',
+            field=models.CharField(verbose_name='version', blank=True, max_length=10, null=True),
+        ),
+    ]

pymess/models/emails.py

@@ -163,6 +163,7 @@ class AbstractEmailTemplate(BaseAbstractTemplate):
     sender = models.EmailField(verbose_name=_('sender'), null=True, blank=True, max_length=200)
     sender_name = models.CharField(verbose_name=_('sender name'), blank=True, null=True, max_length=250)
     variant = models.CharField(verbose_name=_('variant'), max_length=10, null=True, blank=True, editable=False)
+    version = models.CharField(verbose_name=_('version'), max_length=10, null=True, blank=True)
 
     def get_controller(self):
         from pymess.backend.emails import EmailController
@@ -223,8 +224,23 @@ def clean_subject(self, context_data=None):
         super().clean_subject(context_data={'EMAIL_DISABLE_VARIABLE_VALIDATOR': True})
         raise_error_if_contains_banned_tags(self.subject)
 
+    def get_base_template(self):
+        base_template_config = settings.EMAIL_TEMPLATE_BASE_TEMPLATE
+
+        if not base_template_config:
+            raise ValidationError(gettext('EMAIL_TEMPLATE_BASE_TEMPLATE is not set'))
+
+        if isinstance(base_template_config, dict):
+            if not self.version:
+                return next(iter(base_template_config.values()), None)
+
+            return base_template_config.get(self.version)
+
+        return base_template_config
+
+
     def _extend_body(self, template_body):
-        base_template = settings.EMAIL_TEMPLATE_BASE_TEMPLATE
+        base_template = self.get_base_template()
         templatetags = settings.EMAIL_TEMPLATE_TEMPLATETAGS
 
         template_content = '{{% block {} %}}{}{{% endblock %}}'.format(