Update subscribers.py

[hangst]

.values() should return an iterable. Wrapping with another iterable (list) leads to this error.

[ERROR] Exception calling subscribe callback: 'dict_values' object is not callable

[jtbandes]

Hi, can you share some more information and reproduction steps for the bug that's being fixed here? I've added a smoke test in #585 and it would be great if you could update this PR to ensure this code is covered by the tests.

[hangst]

With rosbridge_websocket.py (ros2 branch) running, this script should trigger 'dict_values' object is not callable error.

<script>
const payload = JSON.stringify({
    "op": "subscribe",
    "topic": "/rosout",
})
new WebSocket("ws://localhost:9090").addEventListener("open", function () {
    this.send(payload) // 1st subscription request
    this.send(payload) // 2nd subscription request, triggers error
})
</script>

This error happens when a WebSocket client makes multiple subscription requests on the same topic.

[hangst]

@jtbandes FYI this is the Dockerfile I used to build rosbridge_suite from source.

FROM ros:foxy
WORKDIR /root
RUN git clone --depth 1 --branch ros2 https://github.com/RobotWebTools/rosbridge_suite
RUN apt-get update
RUN rosdep update
RUN rosdep install --default-yes --ignore-src --from-path .
RUN . /opt/ros/foxy/setup.sh && colcon build
CMD ["bash", "-c", ". install/setup.bash && ros2 run rosbridge_server rosbridge_websocket.py"]

rosbridge_websocket.py is executed with the following command.

docker build . --tag rosbridge_suite
docker run -it --net=host rosbridge_suite

[github-actions]

This PR has been marked as stale because it has had no activity in the past 90 days. Please remove the stale label or add a comment to keep it open. Thank you for your contribution.

[jtbandes]

Thanks for the contribution. I am going to close this PR and work from #671 instead, which covers the same problem.