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ROS2 cannot load custom my_package.srv

asked 2022-03-30 05:26:02 -0500

kyubot gravatar image

I am trying to add my custom service to my_package. I created a 'srv' folder under 'my_package' and add "Battery.srv" as below

float64 volt
float64 SOC
float64 current

and added followings to package.xml


and in CMakeLists.txt

find_package(builtin_interfaces REQUIRED)
find_package(rosidl_default_generators REQUIRED)


Also in my

        ('share/ament_index/resource_index/packages', ['resource/' + package_name]),
        ('share/' + package_name, ['package.xml']),
        (os.path.join('share', package_name, 'launch'), glob(os.path.join('launch', '*'))),
        (os.path.join('share', package_name, 'param'), glob(os.path.join('param', '*.yaml'))),
        (os.path.join('share', package_name, 'srv'), glob(os.path.join('srv', '*.srv'))),

Finally in my I tried to import

from my_package.srv import Battery

After colcon build this package successfully, to checked my service I entered below

 $ ros2 interface show my_package/srv/Battery
float64 volt
float64 SOC
float64 current

Now when I tried to run my package node I got error like this

File "/home/my/ros2_ws/build/my_package/my_package/scripts/", line 14, in <module>
    from my_package.srv import Battery
ModuleNotFoundError: No module named 'my_package.srv'

Is there anything wrong with my practice? Any advice would be much appreciated. Kyu

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1 Answer

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answered 2022-03-30 17:02:38 -0500

ljaniec gravatar image

updated 2022-03-30 17:17:18 -0500

Just to be sure - did you source install/setup.bash in your workspace every time (once for the client, once for the server)? You can try to you delete your build and install folders there and rebuild everything too.

Did you create your package with this tutorial?? Because usually messages and services are defined in another package called your_project_interfaces and you import everything from there. Only this part differs in your approach (e.g. based on this and previous link) - you try to do everything in one package, both srv/ and scripts.

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As you said, source ~/bashrc did the trick and it works now. I also realized srv file should not include any Capital letter. Thank you for your comment!

kyubot gravatar image kyubot  ( 2022-03-31 01:11:00 -0500 )edit

I am happy to help! You can mark the answer as accepted then

ljaniec gravatar image ljaniec  ( 2022-03-31 02:05:36 -0500 )edit

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Asked: 2022-03-30 05:26:02 -0500

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Last updated: Mar 30 '22