From 9addff8cfbed80785f604b961fa6ca0a4563e30e Mon Sep 17 00:00:00 2001
From: Chris Caron <lead2gold@gmail.com>
Date: Fri, 23 Aug 2024 16:14:42 -0400
Subject: [PATCH] mqtt:// support for publishing retain flag (#1185)

---
 apprise/plugins/mqtt.py  | 18 ++++++++++++++++--
 test/test_plugin_mqtt.py | 18 ++++++++++++++++++
 2 files changed, 34 insertions(+), 2 deletions(-)

diff --git a/apprise/plugins/mqtt.py b/apprise/plugins/mqtt.py
index 22ab9bfb..4b21bf28 100644
--- a/apprise/plugins/mqtt.py
+++ b/apprise/plugins/mqtt.py
@@ -204,10 +204,15 @@ class NotifyMQTT(NotifyBase):
             'type': 'bool',
             'default': False,
         },
+        'retain': {
+            'name': _('Retain Messages'),
+            'type': 'bool',
+            'default': False,
+        },
     })
 
     def __init__(self, targets=None, version=None, qos=None,
-                 client_id=None, session=None, **kwargs):
+                 client_id=None, session=None, retain=None, **kwargs):
         """
         Initialize MQTT Object
         """
@@ -230,6 +235,10 @@ class NotifyMQTT(NotifyBase):
             if session is None or not self.client_id \
             else parse_bool(session)
 
+        # Our Retain Message Flag
+        self.retain = self.template_args['retain']['default'] \
+            if retain is None else parse_bool(retain)
+
         # Set up our Quality of Service (QoS)
         try:
             self.qos = self.template_args['qos']['default'] \
@@ -376,7 +385,7 @@ class NotifyMQTT(NotifyBase):
                 self.logger.debug('MQTT Payload: %s' % str(body))
 
                 result = self.client.publish(
-                    topic, payload=body, qos=self.qos, retain=False)
+                    topic, payload=body, qos=self.qos, retain=self.retain)
 
                 if result.rc != mqtt.MQTT_ERR_SUCCESS:
                     # Toggle our status
@@ -456,6 +465,7 @@ class NotifyMQTT(NotifyBase):
             'version': self.version,
             'qos': str(self.qos),
             'session': 'yes' if self.session else 'no',
+            'retain': 'yes' if self.retain else 'no',
         }
 
         if self.client_id:
@@ -535,6 +545,10 @@ class NotifyMQTT(NotifyBase):
         if 'session' in results['qsd'] and len(results['qsd']['session']):
             results['session'] = parse_bool(results['qsd']['session'])
 
+        # Message Retain Flag
+        if 'retain' in results['qsd'] and len(results['qsd']['retain']):
+            results['retain'] = parse_bool(results['qsd']['retain'])
+
         # The MQTT Quality of Service to use
         if 'qos' in results['qsd'] and len(results['qsd']['qos']):
             results['qos'] = \
diff --git a/test/test_plugin_mqtt.py b/test/test_plugin_mqtt.py
index 3948b95b..78b8900d 100644
--- a/test/test_plugin_mqtt.py
+++ b/test/test_plugin_mqtt.py
@@ -320,6 +320,24 @@ def test_plugin_mqtt_session_client_id_success(mqtt_client_mock):
     assert re.search(r'my/topic', obj.url())
     assert re.search(r'client_id=apprise', obj.url())
     assert re.search(r'session=yes', obj.url())
+    assert re.search(r'retain=no', obj.url())
+    assert obj.notify(body="test=test") is True
+
+
+def test_plugin_mqtt_retain(mqtt_client_mock):
+    """
+    Verify handling of Retain Message Flag
+    """
+
+    obj = apprise.Apprise.instantiate(
+        'mqtt://user@localhost/my/topic?retain=yes',
+        suppress_exceptions=False)
+
+    assert isinstance(obj, NotifyMQTT)
+    assert obj.url().startswith('mqtt://user@localhost')
+    assert re.search(r'my/topic', obj.url())
+    assert re.search(r'session=no', obj.url())
+    assert re.search(r'retain=yes', obj.url())
     assert obj.notify(body="test=test") is True