Services quiz length error

Course Support ROS Basics In 5 Days (Python)
1

I am stuck on the services quiz. I keep getting the following error:

[INFO] [1634610362.933811, 0.000000]: Doing Service Call…
Traceback (most recent call last):
File “/home/user/catkin_ws/src/services_quiz/src/bb8_move_custom_service_client.py”, line 25, in

result = move_bb8_in_square_service_client(move_bb8_in_square_request_object)

File “/opt/ros/noetic/lib/python3/dist-packages/rospy/impl/tcpros_service.py”, line 442, in call
return self.call(*args, **kwds)
File “/opt/ros/noetic/lib/python3/dist-packages/rospy/impl/tcpros_service.py”, line 522, in call
responses = transport.receive_once()
File “/opt/ros/noetic/lib/python3/dist-packages/rospy/impl/tcpros_base.py”, line 735, in receive_once
p.read_messages(b, msg_queue, sock)
File “/opt/ros/noetic/lib/python3/dist-packages/rospy/impl/tcpros_service.py”, line 360, in read_messages
self._read_ok_byte(b, sock)
File “/opt/ros/noetic/lib/python3/dist-packages/rospy/impl/tcpros_service.py”, line 343, in _read_ok_byte

raise ServiceException(“service [%s] responded with an error: %s”%(self.resolved_name, str))
rospy.service.ServiceException: service [/move_bb8_in_square_custom] responded with an error: b"error processing request: object of type ‘int’ has no len()"

[service_move_bb8_in_square_custom_client-1] process has died [pid 1867, exit code 1, cmd /home/user/catkinProcessing: bb8_move_custom_service_client.py…
_ws/src/services_quiz/src/bb8_move_custom_service_client.py __name:=service_move_bb8_in_square_custom_client __log:=/home/user/.ros/log/de6ab6aa-3082-11ec-9ada-0242c0a82002/service_move_bb8_in_square_custom_client-1.log].
log file: /home/user/.ros/log/de6ab6aa-3082-11ec-9ada-0242c0a82002/service_move_bb8_in_square_custom_client-1*.log

I believe it has to do with a variable that it thinks should be a string. It is obviously this line that is causing the issue:

result = move_bb8_in_square_service_client(move_bb8_in_square_request_object)

Here is my entire client:

Capture
Capture1300×675 78.3 KB

I have looked this over many times and still can’t pinpoint the issue. It is an exact copy of the custom service exercise modified for this exercise. It references the following service:

Capture2
Capture21027×162 19.8 KB

Can anyone see what I did wrong and point me in the right direction? Please let me know if you need more information.

2

The problem could be with you service server code, could you check that? Try calling your service server from the terminal and see if you get the same error.

3

That was it, thanks. I got the same error when calling the service from the terminal. I was using the len() in the range in my for loop.

Is there a way to make BB8 move in the Y direction or am I going to have to turn at the corners in Z?

4

Glad you found the bug!

Turning is in the Z axis. The Y axis if for vertical movement (e.g. drones).