ExecuteProcess cmd parameter treatment 'The passed value needs to be a dictionary in YAML format'

[ddengster]

Bug report

• Operating System:
  Ubuntu 18.04
• Installation type:
  Eloquent
• Version or commit hash:
  Fix parsing of cmd line arguments in XML and yaml file #379 , but should occur in the master branch Only allow ExecuteProcess actions to execute once #375

Steps to reproduce issue

ros2 launch mypkgname mylaunchfile.launch.py

import launch
import launch.actions 
import launch.substitutions 
import launch_ros.actions
import os

from launch_ros.actions import Node

def generate_launch_description():
  
  return launch.LaunchDescription([
    launch.actions.ExecuteProcess(
      name='fake_joint_calibration',
      cmd = ['ros2', 'topic', 'pub', '/calibrated', 'std_msgs/Bool', '"data: 1"'],
      output = 'screen',
      shell='True'
      )
  ])

Expected behavior

The same as running the following on the cmdline

ros2 topic pub /calibrated std_msgs/Bool "data: 1"

Output:

publisher: beginning loop
publishing #1: std_msgs.msg.Bool(data=True)

publishing #2: std_msgs.msg.Bool(data=True)

...

Actual behavior

Output gives:

[fake_joint_calibration-1] The passed value needs to be a dictionary in YAML format

Additional information

I'd also like to know how the cmd parameters work; I've had other related weirdness with my parameters being treated like yaml. Why is that so and is there a workaround for this?

[ivanpauno]

ros2 topic pub expects the value to be a dictionary in yaml format:

def generate_launch_description():
  
  return launch.LaunchDescription([
    launch.actions.ExecuteProcess(
      name='fake_joint_calibration',
      cmd = ['ros2', 'topic', 'pub', '/calibrated', 'std_msgs/Bool', '"{data: True}"'],
      output = 'screen',
      shell='True'
      )
  ])

That should work.

Closing, as it's unrelated to launch.

[jeremy-shannon]

Hi, I know this topic is closed but I was having the same problem and this is the only place I found anything about it whatsoever. I think it's worth noting for anyone else who might come along that I tried your suggestion:

def generate_launch_description():
  
  return launch.LaunchDescription([
    launch.actions.ExecuteProcess(
      name='fake_joint_calibration',
      cmd = ['ros2', 'topic', 'pub', '/calibrated', 'std_msgs/Bool', '"{data: True}"'],
      output = 'screen',
      shell='True'
      )
  ])

...and still got the 'The passed value needs to be a dictionary in YAML format' error. But changing the 'cmd' line to the following (i.e. removing the double quotes) ended up working:

cmd = ['ros2', 'topic', 'pub', '/calibrated', 'std_msgs/Bool', '{data: True}'],

[asymingt]

Thank you @jeremy-shannon -- I spent about an hour trying to work this out, trying various combinations of yaml.dump(), single and double quotations! It was your observation that helped get my code working.

[jeremy-shannon]

@asymingt

Thank you @jeremy-shannon -- I spent about an hour trying to work this out, trying various combinations of yaml.dump(), single and double quotations! It was your observation that helped get my code working.

Nice! I’m glad to hear it helped. 😁