issue-51-telegram work in progress

dsmr_parser/objects.py

@@ -22,15 +22,28 @@ class Telegram(object):
         self._telegram_data = defaultdict(list)
         self._obis_name_mapping = dsmr_parser.obis_name_mapping.EN
         self._reverse_obis_name_mapping = dsmr_parser.obis_name_mapping.REVERSE_EN
-        self._item_names = self._get_item_names()
+        self._item_names = []
 
     def add(self, obis_reference, dsmr_object):
         self._telegram_data[obis_reference].append(dsmr_object)
 
-    def get_by_channel(self, obis_reference, channel):
+        # Update name mapping used to get value by attribute. Example: telegram.P1_MESSAGE_HEADER
+        self._item_names.append(self._obis_name_mapping[obis_reference])
+
+    def get(self, obis_reference, channel=None):
+        """
+        Get value by OBIS reference (regex). If multiple values exist a list is returned, unless filtering by channel.
+        May assume that values are sorted by channel.
+        """
+        if channel is None:
             try:
-            return next(filter(lambda x: x.channel == channel, self._telegram_data[obis_reference]))
-        except StopIteration:
+                return self._telegram_data[obis_reference]
+            except KeyError:
+                raise LookupError('No value found for OBIS reference "{}"'.format(obis_reference))
+
+        try:
+            return [v for v in self._telegram_data[obis_reference] if v.channel == channel][0]
+        except IndexError:
             raise LookupError('No value found for OBIS reference "{}" on channel "{}"'.format(obis_reference, channel))
 
     def __getattr__(self, name):
@@ -41,6 +54,12 @@ class Telegram(object):
         return value
 
     def __getitem__(self, obis_reference):
+        """
+        Has the limitation that it will return the first occurrence of the OBIS reference. Will miss values in case of
+        multiple MBUS devices like gas or water meters. In this case use .get(..) instead.
+
+        Example usage: telegram[obis_references.P1_MESSAGE_HEADER]
+        """
         try:
             return self._telegram_data[obis_reference][0]
         except IndexError:
@@ -48,10 +67,7 @@ class Telegram(object):
             raise KeyError
 
     def __len__(self):
-        return len(self._telegram_data)  # TODO: its nested now
-
-    def _get_item_names(self):
-        return [self._obis_name_mapping[k] for k, v in self._telegram_data.items()]
+        return len(self._telegram_data)
 
     def __iter__(self):
         for attr in self._item_names:

test/test_telegram.py

@@ -321,31 +321,45 @@ class TelegramTest(unittest.TestCase):
 
         assert item_names_tested_set == V4_name_set
 
+    def test_len(self):
+        parser = TelegramParser(telegram_specifications.V5)
+        telegram = parser.parse(TELEGRAM_V5_TWO_MBUS)
+
+        self.assertEqual(len(telegram), 35)
+
     def test_get(self):
+        """ Retrieve MBUS device without supplying channel which fetches all (two) records found. """
         parser = TelegramParser(telegram_specifications.V5)
         telegram = parser.parse(TELEGRAM_V5_TWO_MBUS)
 
-        mbus_1 = telegram.get(obis.HOURLY_GAS_METER_READING, channel=1)
-        mbus_2 = telegram.get(obis.HOURLY_GAS_METER_READING, channel=2)
+        gas_values = telegram.get(obis.HOURLY_GAS_METER_READING)
 
-        self.assertEqual(type(mbus_1), MBusObject)
-        self.assertEqual(mbus_1.channel, 1)
-        self.assertEqual(mbus_1.value, 0)
+        self.assertEqual(len(gas_values), 2)
 
-        self.assertEqual(type(mbus_2), MBusObject)
-        self.assertEqual(mbus_2.channel, 2)
-        self.assertEqual(mbus_2.value, Decimal('246.138'))
+        gas_value_1 = gas_values[0]
+        self.assertEqual(type(gas_value_1), MBusObject)
+        self.assertEqual(gas_value_1.channel, 1)
+        self.assertEqual(gas_value_1.value, 0)
 
-    def test_get_without_channel(self):
-        """ Retrieve MBUS device without supplying channel which fetches the first MBUS record found """
+        gas_value_2 = gas_values[1]
+        self.assertEqual(type(gas_value_2), MBusObject)
+        self.assertEqual(gas_value_2.channel, 2)
+        self.assertEqual(gas_value_2.value, Decimal('246.138'))
+
+    def test_get_with_channel(self):
         parser = TelegramParser(telegram_specifications.V5)
         telegram = parser.parse(TELEGRAM_V5_TWO_MBUS)
 
-        mbus = telegram.get(obis.HOURLY_GAS_METER_READING)
+        gas_value_1 = telegram.get(obis.HOURLY_GAS_METER_READING, channel=1)
+        gas_value_2 = telegram.get(obis.HOURLY_GAS_METER_READING, channel=2)
 
-        self.assertEqual(type(mbus), MBusObject)
-        self.assertEqual(mbus.channel, 1)
-        self.assertEqual(mbus.value, 0)
+        self.assertEqual(type(gas_value_1), MBusObject)
+        self.assertEqual(gas_value_1.channel, 1)
+        self.assertEqual(gas_value_1.value, 0)
+
+        self.assertEqual(type(gas_value_2), MBusObject)
+        self.assertEqual(gas_value_2.channel, 2)
+        self.assertEqual(gas_value_2.value, Decimal('246.138'))
 
     def test_get_unknown_value(self):
         """ Retrieve MBUS device without supplying channel which fetches the first MBUS record found """
@@ -354,13 +368,13 @@ class TelegramTest(unittest.TestCase):
 
         # Test valid OBIS reference with wrong channel
         with self.assertRaises(LookupError) as exception_context:
-            telegram.get_by_channel(obis.HOURLY_GAS_METER_READING, channel=123)
+            telegram.get(obis.HOURLY_GAS_METER_READING, channel=123)
 
         self.assertEqual(
             str(exception_context.exception),
-            'No value found for OBIS reference "\d-\d:24\.2\.1.+?\\r\\n" on channel "123"'
+            'No value found for OBIS reference "\\d-\\d:24\\.2\\.1.+?\\r\\n" on channel "123"'
         )
 
         # Test invalid OBIS reference
         with self.assertRaises(LookupError):
-            telegram.get_by_channel('invalid_obis_reference', channel=1)
+            telegram.get('invalid_obis_reference', channel=1)