2.1.0 Release Notes¶
Channels 2.1 brings a few new major changes to Channels as well as some more minor fixes. In addition, if you’ve not yet seen it, we now have a long-form tutorial to better introduce some of the concepts and sync versus async styles of coding.
Async HTTP Consumer¶
There is a new native-async HTTP consumer class,
channels.generic.http.AsyncHttpConsumer. This allows much easier writing
of long-poll endpoints or other long-lived HTTP connection handling that
benefits from native async support.
You can read more about it in the Consumers documentation.
These consumer classes now all have built-in group join and leave functionality,
which will make a consumer join all group names that are in the iterable
groups on the consumer class (this can be a static list or a
In addition, the
accept methods on both variants now take an optional
subprotocol argument, which will be sent back to the WebSocket client as
the subprotocol the server has selected. The client’s advertised subprotocols
can, as always, be found in the scope as
Nested URL Routing¶
URLRouter instances can now be nested inside each other and, like Django’s
URL handling and
include, will strip off the matched part of the URL in the
outer router and leave only the unmatched portion for the inner router, allowing
reuseable routing files.
Note that you cannot use the Django
include function inside of the
URLRouter as it assumes a bit too much about what it is given as its
left-hand side and will terminate your regular expression/URL pattern wrongly.
Login and Logout¶
As well as overhauling the internals of the
AuthMiddleware, there are now
logout async functions you can call in consumers to
log users in and out of the current session.
Due to the way cookies are sent back to clients, these come with some caveats; read more about them and how to use them properly in Authentication.
In-Memory Channel Layer¶
The in-memory channel layer has been extended to have full expiry and group support so it should now be suitable for drop-in replacement for most test scenarios.
ChannelsLiveServerTestCase has been rewritten to use a new method for
launching Daphne that should be more resilient (and faster), and now shares
code with the Daphne test suite itself.
Ports are now left up to the operating
system to decide rather than being picked from within a set range. It also now
supports static files when the Django
staticfiles app is enabled.
In addition, the Communicator classes have gained a
that allows you to assert that the application didn’t send anything, rather
than writing this yourself using exception handling. See more in the
Origin header validation¶
As well as removing the
It can now also enforce protocol (
https) and port, both
Bugfixes & Small Changes¶
Originvalidation code were removed.
runservercommand now shows the version of Channels you are running.
- Orphaned tasks that may have caused warnings during test runs or occasionally live site traffic are now correctly killed off rather than letting them die later on and print warning messages.
WebsocketCommunicatornow accepts a query string passed into the constructor and adds it to the scope rather than just ignoring it.
- Test handlers will correctly handle changing the
CHANNEL_LAYERSsetting via decorators and wipe the internal channel layer cache.
SessionMiddlewarecan be safely nested inside itself rather than causing a runtime error.
Backwards Incompatible Changes¶
- The format taken by the
OriginValidatorfor its domains has changed and
*.example.comis no longer allowed; instead, use
.example.comto match a domain and all its subdomains.
- If you previously nested
URLRouterinstances inside each other both would have been matching on the full URL before, whereas now they will match on the unmatched portion of the URL, meaning your URL routes would break if you had intended this usage.