Add arg skip_schema_validation to @on()

The argument can be used to skip validation of a request and response.
It defaults to `False`, so by default validation is enabled.

The reasoning for this change is that TMH has charge points which use
measurands inside MeterValues messages which are not compliant with the
OCPP 1.6 specification. Therefore the validation of these messages fail.

With this new argument validation of certain messages can be disabled.

Fixes: #54

Author: Auke Willem Oosterhoff

ocpp/charge_point.py

@@ -140,12 +140,11 @@ async def route_message(self, raw_msg):
             return
 
         if msg.message_type_id == MessageType.Call:
-            # Call's can be validated right away because the 'action' is know.
+            # Call's can be validated right away because the 'action' is known.
             # The 'action' is required to get the correct schema.
             #
             # CallResult's don't have an action field. The action must be
             # deducted from corresponding Call.
-            validate_payload(msg, self._ocpp_version)
             await self._handle_call(msg)
         elif msg.message_type_id in \
                 [MessageType.CallResult, MessageType.CallError]:
@@ -168,6 +167,9 @@ async def _handle_call(self, msg):
             raise NotImplementedError(f"No handler for '{msg.action}' "
                                       "registered.")
 
+        if not handlers.get('_skip_schema_validation', False):
+            validate_payload(msg, self._ocpp_version)
+
         # OCPP uses camelCase for the keys in the payload. It's more pythonic
         # to use snake_case for keyword arguments. Therefore the keys must be
         # 'translated'. Some examples:
@@ -205,7 +207,9 @@ async def _handle_call(self, msg):
         camel_case_payload = snake_to_camel_case(response_payload)
 
         response = msg.create_call_result(camel_case_payload)
-        validate_payload(response, self._ocpp_version)
+
+        if not handlers.get('_skip_schema_validation', False):
+            validate_payload(response, self._ocpp_version)
 
         await self._send(response.to_json())
 

ocpp/routing.py

@@ -1,7 +1,7 @@
 import functools
 
 
-def on(action):
+def on(action, *, skip_schema_validation=False):
     """ Function decorator to mark function as handler for specific action.
 
     This hook's argument are the data that is in the payload for the specific
@@ -20,13 +20,18 @@ def on_boot_notification(charge_point_model, charge_point_vendor, **kwargs): # n
                 status="Accepted",
             )
 
+    The decorator takes an optional argument `skip_schema_validation` which
+    defaults to False. Setting this argument to `True` will disable schema
+    validation of the request and the response of the specific route.
+
     """
     def decorator(func):
         @functools.wraps(func)
         def inner(*args, **kwargs):
             return func(*args, **kwargs)
 
         inner._on_action = action
+        inner._skip_schema_validation = skip_schema_validation
         return inner
     return decorator
 
@@ -79,20 +84,29 @@ def after_boot_notification(self, *args, **kwargs):
             Action.BootNotification: {
                 '_on_action': <reference to 'on_boot_notification'>,
                 '_after_action': <reference to 'after_boot_notification'>,
+                '_skip_schema_validation': False,
             },
         }
 
     """
     routes = {}
     for attr_name in dir(obj):
         attr = getattr(obj, attr_name)
-        for hook in ['_on_action', '_after_action']:
+        for option in ['_on_action', '_after_action']:
             try:
-                action = getattr(attr, hook)
+                action = getattr(attr, option)
 
                 if action not in routes:
                     routes[action] = {}
-                routes[action][hook] = attr
+
+                # Routes decorated with the `@on()` decorator can be configured
+                # to skip validation of the input and output. For more info see
+                # the docstring of `on()`.
+                if option == '_on_action':
+                    routes[action]['_skip_schema_validation'] = \
+                        getattr(attr, '_skip_schema_validation', False)
+
+                routes[action][option] = attr
 
             except AttributeError:
                 continue

tests/test_routing.py

@@ -9,7 +9,7 @@ def test_create_route_map():
 
     """
     class ChargePoint:
-        @on(Action.Heartbeat)
+        @on(Action.Heartbeat, skip_schema_validation=True)
         def on_heartbeat(self):
             pass
 
@@ -31,8 +31,10 @@ def undecorated(self):
         Action.Heartbeat: {
             '_on_action': cp.on_heartbeat,
             '_after_action': cp.after_heartbeat,
+            '_skip_schema_validation': True,
         },
         Action.MeterValues: {
             '_on_action': cp.meter_values,
+            '_skip_schema_validation': False,
         },
     }

tests/v16/test_v16_charge_point.py

@@ -1,6 +1,7 @@
 import json
 import pytest
 import asyncio
+from unittest import mock
 
 from ocpp.exceptions import NotImplementedError
 from ocpp.routing import on, after, create_route_map
@@ -52,6 +53,45 @@ def after_boot_notification(charge_point_model, charge_point_vendor,
     )
 
 
+@pytest.mark.asyncio
+async def test_route_message_without_validation(base_central_system):
+    @on(Action.BootNotification, skip_schema_validation=True)
+    def on_boot_notification(**kwargs):  # noqa
+        assert kwargs['firmware_version'] == "#1:3.4.0-2990#N:217H;1.0-223"
+
+        return call_result.BootNotificationPayload(
+            current_time='2018-05-29T17:37:05.495259',
+            interval=350,
+            # 'Yolo' is not a valid value for for field status.
+            status='Yolo',
+        )
+
+    setattr(base_central_system, 'on_boot_notification', on_boot_notification)
+    base_central_system.route_map = create_route_map(base_central_system)
+
+    await base_central_system.route_message(json.dumps([
+        2,
+        1,
+        "BootNotification",
+        {
+            # The payload is missing the required fields 'chargepointVendor'
+            # and 'chargePointModel'.
+            "firmwareVersion": "#1:3.4.0-2990#N:217H;1.0-223"
+        }
+    ]))
+
+    base_central_system._connection.send.call_args == \
+        mock.call(json.dumps([
+            3,
+            "1",
+            {
+                'currentTime': '2018-05-29T17:37:05.495259',
+                'interval': 350,
+                'status': 'Yolo',
+            }
+        ]))
+
+
 @pytest.mark.asyncio
 async def test_route_message_with_no_route(base_central_system,
                                            heartbeat_call):