Merge pull request #12 from KixPanganiban/feature/request-event-middl…

…eware

Added RequestEventMiddleware and the ability to access the request_event

CHANGES

@@ -3,6 +3,15 @@ Zask Changelog
 
 Here you can see the full list of changes between each Zask release.
 
+Version 1.9.3
+-------------
+
+released on July 28th 2016
+
+* Added RequestEventMiddleware
+* request_event now accessible inside service endpoint via get_request_event()
+
+
 Version 1.9.2
 -------------
 

zask/__init__.py

@@ -1,6 +1,6 @@
 # -*- coding: utf-8 -*-
 
-__version__ = '1.9.2'
+__version__ = '1.9.3'
 
 import gevent
 from gevent.local import local

zask/ext/zerorpc/__init__.py

@@ -47,10 +47,12 @@
 CONFIG_CUSTOME_HEADER_MIDDLEWARE = 'header'
 ACCESS_LOG_MIDDLEWARE = 'access_log'
 REQUEST_CHAIN_MIDDLEWARE = 'uuid'
+REQUEST_EVENT_MIDDLEWARE = 'event'
 DEFAULT_MIDDLEWARES = [
     CONFIG_CUSTOME_HEADER_MIDDLEWARE,
     REQUEST_CHAIN_MIDDLEWARE,
-    ACCESS_LOG_MIDDLEWARE
+    ACCESS_LOG_MIDDLEWARE,
+    REQUEST_EVENT_MIDDLEWARE
 ]
 
 
@@ -235,6 +237,15 @@ def client_before_request(self, event):
                 'uuid': self.get_uuid(),
             })
 
+class RequestEventMiddleware(object):
+    """Exposes the request_event to the object being passed to Server()
+    via self.get_request_event() from a service endpoint.
+    """
+
+    def server_before_exec(self, request_event):
+        """Injects the request_event into greenlet's local storage context.
+        """
+        setattr(_request_ctx.stash, 'request_event', request_event)
 
 class AccessLogMiddleware(object):
 
@@ -386,6 +397,10 @@ def _init_zerorpc_context(self):
 
         if ACCESS_LOG_MIDDLEWARE in self._middlewares:
             context.register_middleware(AccessLogMiddleware(self.app))
+
+        if REQUEST_EVENT_MIDDLEWARE in self._middlewares:
+            context.register_middleware(RequestEventMiddleware())
+
         _Server.__context__ = _Client.__context__ = context
 
     def register_middleware(self, middleware):
@@ -436,6 +451,10 @@ def __init__(self, methods=None, context=None, **kargs):
                                 heartbeat=heartbeat,
                                 **kargs)
 
+        # Inject get_request_event *after* Server constructor so that
+        # it's not exposed to the RPC from the outside.
+        methods.get_request_event = self._get_request_event
+
         for instance in context_._middlewares:
             if isinstance(instance, ConfigEndpointMiddleware):
                 if methods.__version__ is None:
@@ -449,6 +468,16 @@ def __init__(self, methods=None, context=None, **kargs):
             if isinstance(instance, AccessLogMiddleware):
                 instance.set_class_name(methods.__class__.__name__)
 
+    def _get_request_event(self):
+        """Returns the request_event from the local greenlet storage.
+        Requires RequestEventMiddleware to be enabled to work.
+        """
+        enabled_middlewares = [mw.__class__.__name__ for mw in
+                               self.__context__._middlewares]
+        if 'RequestEventMiddleware' not in enabled_middlewares:
+            raise MissingMiddlewareException('RequestEventMiddleware')
+        return getattr(_request_ctx.stash, 'request_event')
+
 
 class _Client(zerorpc.Client):
 
@@ -585,3 +614,15 @@ class NoNameException(Exception):
 
     def __str__(self):
         return "__service_name__ is needed for ZeroRPC server"
+
+
+class MissingMiddlewareException(Exception):
+    """Raised when Zask tries to invoke a functionality provided
+    by a specific middleware, but that middleware is not loaded.
+    """
+
+    def __init__(self, middleware):
+        self.middleware = middleware
+
+    def __str__(self):
+        return 'Missing required middleware {}.'.format(self.middleware)