Implement send_channel_session

channels/decorators.py

@@ -1,5 +1,8 @@
 import functools
+import hashlib
+from importlib import import_module
 
+from django.conf import settings
 from django.utils import six
 
 from channels import channel_backends, DEFAULT_CHANNEL_BACKEND
@@ -24,3 +27,34 @@ def consumer(*channels, **kwargs):
 
 
 # TODO: Sessions, auth
+
+def send_channel_session(func):
+    """
+    Provides a session-like object called "channel_session" to consumers
+    as a message attribute that will auto-persist across consumers with
+    the same incoming "send_channel" value.
+    """
+    @functools.wraps(func)
+    def inner(*args, **kwargs):
+        # Make sure there's a send_channel in kwargs
+        if "send_channel" not in kwargs:
+            raise ValueError("No send_channel sent to consumer; this decorator can only be used on messages containing it.")
+        # Turn the send_channel into a valid session key length thing.
+        # We take the last 24 bytes verbatim, as these are the random section,
+        # and then hash the remaining ones onto the start, and add a prefix
+        # TODO: See if there's a better way of doing this
+        session_key = "skt" + hashlib.md5(kwargs['send_channel'][:-24]).hexdigest()[:8] + kwargs['send_channel'][-24:]
+        # Make a session storage
+        session_engine = import_module(settings.SESSION_ENGINE)
+        session = session_engine.SessionStore(session_key=session_key)
+        # If the session does not already exist, save to force our session key to be valid
+        if not session.exists(session.session_key):
+            session.save()
+        kwargs['channel_session'] = session
+        # Run the consumer
+        result = func(*args, **kwargs)
+        # Persist session if needed (won't be saved if error happens)
+        if session.modified:
+            session.save()
+        return result
+    return inner

docs/getting-started.rst

@@ -275,7 +275,7 @@ However, that session is based on cookies, and so follows the user round the
 site - it's great for information that should persist across all WebSocket and
 HTTP connections, but not great for information that is specific to a single
 WebSocket (such as "which chatroom should this socket be connected to"). For
-this reason, Channels also provides a ``websocker_channel_session`` decorator,
+this reason, Channels also provides a ``send_channel_session`` decorator,
 which adds a ``channel_session`` attribute to the message; this works just like
 the normal ``session`` attribute, and persists to the same storage, but varies
 per-channel rather than per-cookie.
@@ -284,10 +284,10 @@ Let's use it now to build a chat server that expects you to pass a chatroom
 name in the path of your WebSocket request (we'll ignore auth for now)::
 
     from channels import Channel
-    from channels.decorators import consumer, websocket_channel_session
+    from channels.decorators import consumer, send_channel_session
 
     @consumer("django.websocket.connect")
-    @websocket_channel_session
+    @send_channel_session
     def ws_connect(channel, send_channel, path, channel_session, **kwargs):
         # Work out room name from path (ignore slashes)
         room = path.strip("/")
@@ -296,17 +296,17 @@ name in the path of your WebSocket request (we'll ignore auth for now)::
         Group("chat-%s" % room).add(send_channel)
 
     @consumer("django.websocket.keepalive")
-    @websocket_channel_session
+    @send_channel_session
     def ws_add(channel, send_channel, channel_session, **kwargs):
         Group("chat-%s" % channel_session['room']).add(send_channel)
 
     @consumer("django.websocket.receive")
-    @websocket_channel_session
+    @send_channel_session
     def ws_message(channel, send_channel, content, channel_session, **kwargs):
         Group("chat-%s" % channel_session['room']).send(content=content)
 
     @consumer("django.websocket.disconnect")
-    @websocket_channel_session
+    @send_channel_session
     def ws_disconnect(channel, send_channel, channel_session, **kwargs):
         Group("chat-%s" % channel_session['room']).discard(send_channel)
 
@@ -340,7 +340,7 @@ Let's see what that looks like, assuming we
 have a ChatMessage model with ``message`` and ``room`` fields::
 
     from channels import Channel
-    from channels.decorators import consumer, websocket_channel_session
+    from channels.decorators import consumer, send_channel_session
     from .models import ChatMessage
 
     @consumer("chat-messages")
@@ -351,7 +351,7 @@ have a ChatMessage model with ``message`` and ``room`` fields::
         Group("chat-%s" % room).send(message)
 
     @consumer("django.websocket.connect")
-    @websocket_channel_session
+    @send_channel_session
     def ws_connect(channel, send_channel, path, channel_session, **kwargs):
         # Work out room name from path (ignore slashes)
         room = path.strip("/")
@@ -360,18 +360,18 @@ have a ChatMessage model with ``message`` and ``room`` fields::
         Group("chat-%s" % room).add(send_channel)
 
     @consumer("django.websocket.keepalive")
-    @websocket_channel_session
+    @send_channel_session
     def ws_add(channel, send_channel, channel_session, **kwargs):
         Group("chat-%s" % channel_session['room']).add(send_channel)
 
     @consumer("django.websocket.receive")
-    @websocket_channel_session
+    @send_channel_session
     def ws_message(channel, send_channel, content, channel_session, **kwargs):
         # Stick the message onto the processing queue
         Channel("chat-messages").send(room=channel_session['room'], message=content)
 
     @consumer("django.websocket.disconnect")
-    @websocket_channel_session
+    @send_channel_session
     def ws_disconnect(channel, send_channel, channel_session, **kwargs):
         Group("chat-%s" % channel_session['room']).discard(send_channel)