Exception calling subscribe callback: 'float' object has no attribute 'get_fields_and_field_types'

[owen7900]

Expected Behavior

Sending rmf_fleet_msgs/FleetState messages through the websocket to the front end.

Actual Behavior

Subscribe is failing giving this error message

---
stamp:
  sec: 1593087409
  nanosec: 113872237
level: 40
name: rosbridge_websocket
msg: 'Exception calling subscribe callback: ''float'' object has no attribute ''get_fields_and_field_types'''
file: /home/owen/server_ws/install/rosbridge_library/lib/python3.6/site-packages/rosbridge_library/internal/subscribers.py
function: callback
line: 192
---

This only occurs when the FleetState message has robots in the Array of Robot states. when the Array is empty there is no problem.

Steps to Reproduce the Problem

1.Use roslibjs to subscribe to a topic publishing an rmf_fleet_msgs/FleetState message
2.Send a FleetState message with a non-empty RobotState Array

Specifications

• ROS Version (echo $ROS_DISTRO): Ros2 Eloquent
• OS Version (grep DISTRIB_CODENAME /etc/lsb-release): Bionic
• Rosbridge Version (roscat rosbridge_server package.xml | grep '<version>'): ros2 branch built from source
• Twisted Version (python -c 'import twisted; print twisted.version'): 17.9.0

[owen7900]

In further testing I have found this error also occurs with a std_msgs/msg/Float32 message as well. I will continue adding to this issue as I find more msg types that throw this error.

[github-actions]

This issue has been marked as stale because it has been open for 180 days with no activity. Please remove the stale label or add a comment to keep it open.

[danidask]

Same issue

Subscribe to a topic publishing std_msgs/msg/Int32MultiArray from javascript frontend through websocket

Steps to Reproduce the Problem

ros2 topic pub /test std_msgs/msg/Int32MultiArray "data: [1, 2]"

  let test_topic = new ROSLIB.Topic({
    ros: ros,
    name: '/test',
    messageType: 'std_msgs/msg/Int32MultiArray'
  })
  test_topic.subscribe(function(message) {
    console.log(message.data)
  })

rosbridge_server log:
[rosbridge_websocket-1] [ERROR] [1629385982.186968150] [rosbridge_websocket]: Exception calling subscribe callback: 'array.array' object has no attribute 'get_fields_and_field_types'

Specifications

ROS2 Foxy
Docker image Ubuntu 20.04 Focal
Host Ubuntu 18.04 Bionic
Python 3.8.10
rosbridge_server 1.0.2 (ros2 branch built from source)

[jtbandes]

I'm not able to reproduce this issue on Galactic. Will try Foxy soon.

[jtbandes]

@danidask Are you using multiple subscribers (multiple clients) at once? Can you try building from latest source?

I can reproduce some issues, although not the exact error message, if I have one cbor-raw subscriber and one json subscriber (the code in your example) to the same topic:

[rosbridge_websocket-1] [ERROR] [1629395850.023210277] [rosbridge_websocket]: Exception calling subscribe callback: Traceback (most recent call last):
[rosbridge_websocket-1]   File "/home/parallels/Desktop/rosbridge_suite/install/rosbridge_library/lib/python3.8/site-packages/rosbridge_library/internal/subscribers.py", line 189, in callback
[rosbridge_websocket-1]     callback(outgoing)
[rosbridge_websocket-1] TypeError: 'dict_values' object is not callable
[rosbridge_websocket-1] 
[rosbridge_websocket-1] [ERROR] [1629395851.020892139] [rosbridge_websocket]: Exception calling subscribe callback: Traceback (most recent call last):
[rosbridge_websocket-1]   File "/home/parallels/Desktop/rosbridge_suite/install/rosbridge_library/lib/python3.8/site-packages/rosbridge_library/internal/subscribers.py", line 189, in callback
[rosbridge_websocket-1]     callback(outgoing)
[rosbridge_websocket-1]   File "/home/parallels/Desktop/rosbridge_suite/install/rosbridge_library/lib/python3.8/site-packages/rosbridge_library/capabilities/subscribe.py", line 163, in on_msg
[rosbridge_websocket-1]     self.handler.handle_message(msg)
[rosbridge_websocket-1]   File "/home/parallels/Desktop/rosbridge_suite/install/rosbridge_library/lib/python3.8/site-packages/rosbridge_library/internal/subscription_modifiers.py", line 70, in handle_message
[rosbridge_websocket-1]     self.publish(msg)
[rosbridge_websocket-1]   File "/home/parallels/Desktop/rosbridge_suite/install/rosbridge_library/lib/python3.8/site-packages/rosbridge_library/capabilities/subscribe.py", line 152, in _publish
[rosbridge_websocket-1]     self.publish(message, self.fragment_size, self.compression)
[rosbridge_websocket-1]   File "/home/parallels/Desktop/rosbridge_suite/install/rosbridge_library/lib/python3.8/site-packages/rosbridge_library/capabilities/subscribe.py", line 333, in publish
[rosbridge_websocket-1]     outgoing_msg = bytearray(encode_cbor(outgoing_msg))
[rosbridge_websocket-1] ValueError: cannot serialize unknown object: std_msgs.msg.Int32MultiArray(layout=std_msgs.msg.MultiArrayLayout(dim=[], data_offset=0), data=[1, 2])
[rosbridge_websocket-1] 

Neither of these error messages are the ones reported in this issue, though — one of them is #562 and one is #610.

[danidask]

@jtbandes thanks for taking the time to look at it.
I rebuild it from the last source code, and now is working as expected. Its nice to see it’s in active development (the source I had was only few days old)
I checked having several clients at once and still works.

[github-actions]

This issue has been marked as stale because there has been no activity in the past 6 months. Please add a comment to keep it open.