Get request object in eventstream

[Samiddha99]

Using view we can get the user information from request object. But in eventstream there have no request object. So in eventstream how can I get the user information? Suppose, url of an eventstream is "/events/". So when from client device a connection will be made with the event, then this event will only streaming the data related to this user. I can do that by using client's username in eventstream url. I don't want to pass username with url for security reasons.

[jkarneges]

Hi,

The docs are light in details, but determining channels from a request is described here. At the end of that section it says you can do advanced mapping using a channel manager. For an example of a channel manager, see this section.

In the channel manger, you'll want to reimplement get_channels_for_request. You can see the default implementation here. But in your reimplementation you could do anything. And the current request is supplied as an argument.

[Samiddha99]

I do this -

In myapp.channelmanager.py

from django_eventstream.channelmanager import ChannelManagerBase

class CustomChannelManager(ChannelManagerBase):
    def get_channels_for_request(self, request, view_kwargs):
        if 'format-channels' in view_kwargs:
            channel = str(view_kwargs['format-channels'])
            channel = channel.format(request.user.username)
            return set(channel)
        elif 'channels' in view_kwargs:
            return set(view_kwargs['channels'])
        elif 'channel' in view_kwargs:
            return set([view_kwargs['channel']])
        else:
            return set(request.GET.getlist('channel'))

In settings.py EVENTSTREAM_CHANNELMANAGER_CLASS = 'myapp.channelmanager.CustomChannelManager

In myapp.urls.py

import django_eventstream
urlpatterns += [path('events/', include(django_eventstream.urls), { 'format-channels': ['customuser-{}'] }),]

In asgi.py

os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'project.settings')

application = ProtocolTypeRouter({
    'http': URLRouter([

        url(r'^events/', AuthMiddlewareStack(URLRouter(
            django_eventstream.routing.urlpatterns
        )),{ 'format-channels': ['customuser-{}'] }),

        url(r'', get_asgi_application()),

    ]),
})

But when I go to the url http://127.0.0.1:8000/events/ I am getting the following response -

{
"condition": "bad-request",
"text": "Invalid request: Channel limit exceeded."
}

[jkarneges]

Hi,

I think this code is wrong:

channel = str(view_kwargs['format-channels'])
channel = channel.format(request.user.username)
return set(channel)

Probably it should be something like:

channel = view_kwargs['format-channels'][0]
channel = channel.format(request.user.username)
return set([channel])

[Samiddha99]

After make changes in myapp.channelmanager.py according to suggestion, the events are loading, i.e. when I go to the url http://127.0.0.1:8000/events/ , the link continually loading, it's not showing anything in the web page (in the browser tab the loading Spiner spinning). I put a print(), in get_channels_for_request() function to check if it works:

channel = view_kwargs['format-channels'][0]
channel = channel.format(request.user.username)
print(channel)
return set([channel])

I noticed that it successfully print the channel name - "customuser-Admin" (I logged in with username Admin). So what to do now?

[jkarneges]

By "go to the url" do you mean you tried to browse to it? That won't really work. You need to connect to the events URL using EventSource in JS.

[Samiddha99]

To check it with EventSource, I try to send an event to the streaming with send_event('customuser-{}'.format(request.user.username), 'message', 'mydata') from views, and I get NotImplementedError()

[jkarneges]

Ah, try inheriting from DefaultChannelManager rather than ChannelManagerBase.

[Samiddha99]

Thanks, problem solved