[SOLVED] ModuleNotFoundError: No module named 'my_custom_service_pkg'

Course Support ROS Basics In 5 Days (Python)
21

Thank You for the help I appreciate it. How can I upload the files it says that the allowed formats are only pictures.

22

Hi @IdrisOm ,

Thanks for sharing the files.

For now I have fixed the my_custom_srv_msg_pkg package. Your custom message format is correct, I am assuming you copy-pasted from tutorial.

Your CMakeLists.txt had two problems: I have fixed it!

  1. You forgot to include rospy under find_package
  2. You should include std_msgs under catkin_package and remove my_custom_srv_msg_pkg

Your package.xml had the dependencies in wrong order: I have fixed this also!

Here are your modified (fixed) files for my_custom_srv_msg_pkg package: copy-paste into your files.

CMakeLists.txt

cmake_minimum_required(VERSION 3.0.2)
project(my_custom_srv_msg_pkg)


## Here is where all the packages needed to COMPILE the messages of topics, services and actions go.
## It's only getting its paths, and not really importing them to be used in the compilation.
## It's only for further functions in CMakeLists.txt to be able to find those packages.
## In package.xml you have to state them as build
find_package(catkin REQUIRED COMPONENTS
  rospy
  std_msgs
  message_generation
)

## Generate services in the 'srv' folder
## In this function will be all the action messages of this package ( in the action folder ) to be compiled.
## You can state that it gets all the actions inside the action directory: DIRECTORY action
## Or just the action messages stated explicitly: FILES my_custom_action.action
## In your case you only need to do one of two things, as you wish.
add_service_files(
  FILES
  MyCustomServiceMessage.srv
)

## Here is where the packages needed for the action messages compilation are imported.
generate_messages(
  DEPENDENCIES
  std_msgs
)

## State here all the packages that will be needed by someone that executes something from your package.
## All the packages stated here must be in the package.xml as exec_depend
catkin_package(
  CATKIN_DEPENDS rospy std_msgs
)


include_directories(
  ${catkin_INCLUDE_DIRS}
)

package.xml

<?xml version="1.0"?>
<package format="2">
  <name>my_custom_srv_msg_pkg</name>
  <version>0.0.0</version>
  <description>The my_custom_srv_msg_pkg package</description>

  <maintainer email="user@todo.todo">user</maintainer>

  <license>TODO</license>

  <buildtool_depend>catkin</buildtool_depend>
  
  <build_depend>rospy</build_depend>
  <build_depend>std_msgs</build_depend>
  <build_depend>message_generation</build_depend>
  
  <build_export_depend>rospy</build_export_depend>
  <build_export_depend>std_msgs</build_export_depend>
  <build_export_depend>message_runtime</build_export_depend>
  
  <exec_depend>rospy</exec_depend>
  <exec_depend>std_msgs</exec_depend>
  <exec_depend>message_runtime</exec_depend>

  <export>
  </export>
</package>

Regards,
Girish

23

Hi @IdrisOm ,

Fixed your my_examples_pkg package.

Here are the problems you had:

  1. You imported my_custom_service_pkg.srv instead of my_custom_srv_msg_pkg.srv - so there was wrong package name - which is why you got module not found error - because my_custom_service_pkg never existed.
  2. In your CMakeLists.txt file:
    a. You do not require message_generation under find_package - I removed that line.
    b. You do not require MyCustomServiceMessage.srv under add_service_files - I removed that line.
    c. You do not require add_dependencies(my_custom_srv_msg_pkg ${catkin_EXPORTED_TARGETS})
    d. You do not require my_custom_srv_msg_pkg under catkin_package
  3. Your package.xml file was not in proper order.

Now everything is fixed and tested.

Here are your modified files:

custom_service_server.py:

#! /usr/bin/env python

import rospy
from my_custom_srv_msg_pkg.srv import MyCustomServiceMessage, MyCustomServiceMessageResponse


def my_callback(request):

    print("Request Data==> duration="+str(request.duration))
    my_response = MyCustomServiceMessageResponse()
    if request.duration > 5.0:
        my_response.success = True
    else:
        my_response.success = False
    # the service Response class, in this case MyCustomServiceMessageResponse
    return my_response


rospy.init_node('service_client')
# create the Service called my_service with the defined callback
my_service = rospy.Service('/my_service', MyCustomServiceMessage, my_callback)
rospy.spin()  # maintain the service open.

CMakeLists.txt:

cmake_minimum_required(VERSION 3.0.2)
project(my_examples_pkg)

## Compile as C++11, supported in ROS Kinetic and newer
# add_compile_options(-std=c++11)

## Find catkin macros and libraries
## if COMPONENTS list like find_package(catkin REQUIRED COMPONENTS xyz)
## is used, also find other catkin packages
find_package(catkin REQUIRED COMPONENTS
  rospy
  std_msgs
  my_custom_srv_msg_pkg
)

## System dependencies are found with CMake's conventions
# find_package(Boost REQUIRED COMPONENTS system)


## Uncomment this if the package has a setup.py. This macro ensures
## modules and global scripts declared therein get installed
## See http://ros.org/doc/api/catkin/html/user_guide/setup_dot_py.html
# catkin_python_setup()

################################################
## Declare ROS messages, services and actions ##
################################################

## To declare and build messages, services or actions from within this
## package, follow these steps:
## * Let MSG_DEP_SET be the set of packages whose message types you use in
##   your messages/services/actions (e.g. std_msgs, actionlib_msgs, ...).
## * In the file package.xml:
##   * add a build_depend tag for "message_generation"
##   * add a build_depend and a exec_depend tag for each package in MSG_DEP_SET
##   * If MSG_DEP_SET isn't empty the following dependency has been pulled in
##     but can be declared for certainty nonetheless:
##     * add a exec_depend tag for "message_runtime"
## * In this file (CMakeLists.txt):
##   * add "message_generation" and every package in MSG_DEP_SET to
##     find_package(catkin REQUIRED COMPONENTS ...)
##   * add "message_runtime" and every package in MSG_DEP_SET to
##     catkin_package(CATKIN_DEPENDS ...)
##   * uncomment the add_*_files sections below as needed
##     and list every .msg/.srv/.action file to be processed
##   * uncomment the generate_messages entry below
##   * add every package in MSG_DEP_SET to generate_messages(DEPENDENCIES ...)

## Generate messages in the 'msg' folder
add_message_files(
   FILES
   Age.msg
#   Message1.msg
#   Message2.msg
 )

## Generate services in the 'srv' folder
#add_service_files(
#   FILES
#   Service1.srv
#   Service2.srv
#)

## Generate actions in the 'action' folder
#add_action_files(
#   FILES
#   Action1.action
#   Action2.action
#)

## Generate added messages and services with any dependencies listed here
generate_messages(
   DEPENDENCIES
   std_msgs
 )

################################################
## Declare ROS dynamic reconfigure parameters ##
################################################

## To declare and build dynamic reconfigure parameters within this
## package, follow these steps:
## * In the file package.xml:
##   * add a build_depend and a exec_depend tag for "dynamic_reconfigure"
## * In this file (CMakeLists.txt):
##   * add "dynamic_reconfigure" to
##     find_package(catkin REQUIRED COMPONENTS ...)
##   * uncomment the "generate_dynamic_reconfigure_options" section below
##     and list every .cfg file to be processed

## Generate dynamic reconfigure parameters in the 'cfg' folder
# generate_dynamic_reconfigure_options(
#   cfg/DynReconf1.cfg
#   cfg/DynReconf2.cfg
# )

###################################
## catkin specific configuration ##
###################################
## The catkin_package macro generates cmake config files for your package
## Declare things to be passed to dependent projects
## INCLUDE_DIRS: uncomment this if your package contains header files
## LIBRARIES: libraries you create in this project that dependent projects also need
## CATKIN_DEPENDS: catkin_packages dependent projects also need
## DEPENDS: system dependencies of this project that dependent projects also need
catkin_package(
#  INCLUDE_DIRS include
#  LIBRARIES my_examples_pkg
   CATKIN_DEPENDS rospy std_msgs
#  DEPENDS system_lib
)

###########
## Build ##
###########

## Specify additional locations of header files
## Your package locations should be listed before other locations
include_directories(
# include
  ${catkin_INCLUDE_DIRS}
)

## Declare a C++ library
# add_library(${PROJECT_NAME}
#   src/${PROJECT_NAME}/my_examples_pkg.cpp
# )

## Add cmake target dependencies of the library
## as an example, code may need to be generated before libraries
## either from message generation or dynamic reconfigure
# add_dependencies(${PROJECT_NAME} ${${PROJECT_NAME}_EXPORTED_TARGETS} ${catkin_EXPORTED_TARGETS})


## Declare a C++ executable
## With catkin_make all packages are built within a single CMake context
## The recommended prefix ensures that target names across packages don't collide
# add_executable(${PROJECT_NAME}_node src/my_examples_pkg_node.cpp)

## Rename C++ executable without prefix
## The above recommended prefix causes long target names, the following renames the
## target back to the shorter version for ease of user use
## e.g. "rosrun someones_pkg node" instead of "rosrun someones_pkg someones_pkg_node"
# set_target_properties(${PROJECT_NAME}_node PROPERTIES OUTPUT_NAME node PREFIX "")

## Add cmake target dependencies of the executable
## same as for the library above
# add_dependencies(${PROJECT_NAME}_node ${${PROJECT_NAME}_EXPORTED_TARGETS} ${catkin_EXPORTED_TARGETS})

## Specify libraries to link a library or executable target against
# target_link_libraries(${PROJECT_NAME}_node
#   ${catkin_LIBRARIES}
# )

#############
## Install ##
#############

# all install targets should use catkin DESTINATION variables
# See http://ros.org/doc/api/catkin/html/adv_user_guide/variables.html

## Mark executable scripts (Python etc.) for installation
## in contrast to setup.py, you can choose the destination
# catkin_install_python(PROGRAMS
#   scripts/my_python_script
#   DESTINATION ${CATKIN_PACKAGE_BIN_DESTINATION}
# )

## Mark executables for installation
## See http://docs.ros.org/melodic/api/catkin/html/howto/format1/building_executables.html
# install(TARGETS ${PROJECT_NAME}_node
#   RUNTIME DESTINATION ${CATKIN_PACKAGE_BIN_DESTINATION}
# )

## Mark libraries for installation
## See http://docs.ros.org/melodic/api/catkin/html/howto/format1/building_libraries.html
# install(TARGETS ${PROJECT_NAME}
#   ARCHIVE DESTINATION ${CATKIN_PACKAGE_LIB_DESTINATION}
#   LIBRARY DESTINATION ${CATKIN_PACKAGE_LIB_DESTINATION}
#   RUNTIME DESTINATION ${CATKIN_GLOBAL_BIN_DESTINATION}
# )

## Mark cpp header files for installation
# install(DIRECTORY include/${PROJECT_NAME}/
#   DESTINATION ${CATKIN_PACKAGE_INCLUDE_DESTINATION}
#   FILES_MATCHING PATTERN "*.h"
#   PATTERN ".svn" EXCLUDE
# )

## Mark other files for installation (e.g. launch and bag files, etc.)
# install(FILES
#   # myfile1
#   # myfile2
#   DESTINATION ${CATKIN_PACKAGE_SHARE_DESTINATION}
# )

#############
## Testing ##
#############

## Add gtest based cpp test target and link libraries
# catkin_add_gtest(${PROJECT_NAME}-test test/test_my_examples_pkg.cpp)
# if(TARGET ${PROJECT_NAME}-test)
#   target_link_libraries(${PROJECT_NAME}-test ${PROJECT_NAME})
# endif()

## Add folders to be run by python nosetests
# catkin_add_nosetests(test)

package.xml:

<?xml version="1.0"?>
<package format="2">
  <name>my_examples_pkg</name>
  <version>0.0.0</version>
  <description>The my_examples_pkg package</description>

  <!-- One maintainer tag required, multiple allowed, one person per tag -->
  <!-- Example:  -->
  <!-- <maintainer email="jane.doe@example.com">Jane Doe</maintainer> -->
  <maintainer email="user@todo.todo">user</maintainer>


  <!-- One license tag required, multiple allowed, one license per tag -->
  <!-- Commonly used license strings: -->
  <!--   BSD, MIT, Boost Software License, GPLv2, GPLv3, LGPLv2.1, LGPLv3 -->
  <license>TODO</license>


  <!-- Url tags are optional, but multiple are allowed, one per tag -->
  <!-- Optional attribute type can be: website, bugtracker, or repository -->
  <!-- Example: -->
  <!-- <url type="website">http://wiki.ros.org/my_examples_pkg</url> -->


  <!-- Author tags are optional, multiple are allowed, one per tag -->
  <!-- Authors do not have to be maintainers, but could be -->
  <!-- Example: -->
  <!-- <author email="jane.doe@example.com">Jane Doe</author> -->


  <!-- The *depend tags are used to specify dependencies -->
  <!-- Dependencies can be catkin packages or system dependencies -->
  <!-- Examples: -->
  <!-- Use depend as a shortcut for packages that are both build and exec dependencies -->
  <!--   <depend>roscpp</depend> -->
  <!--   Note that this is equivalent to the following: -->
  <!--   <build_depend>roscpp</build_depend> -->
  <!--   <exec_depend>roscpp</exec_depend> -->
  <!-- Use build_depend for packages you need at compile time: -->
  <!--   <build_depend>message_generation</build_depend> -->
  <!-- Use build_export_depend for packages you need in order to build against this package: -->
  <!--   <build_export_depend>message_generation</build_export_depend> -->
  <!-- Use buildtool_depend for build tool packages: -->
  <!--   <buildtool_depend>catkin</buildtool_depend> -->
  <!-- Use exec_depend for packages you need at runtime: -->
  <!--   <exec_depend>message_runtime</exec_depend> -->
  <!-- Use test_depend for packages you need only for testing: -->
  <!--   <test_depend>gtest</test_depend> -->
  <!-- Use doc_depend for packages you need only for building documentation: -->
  <!--   <doc_depend>doxygen</doc_depend> -->
  <buildtool_depend>catkin</buildtool_depend>

  <build_depend>rospy</build_depend>
  <build_depend>std_msgs</build_depend>
  <build_depend>my_custom_srv_msg_pkg</build_depend>
  <build_depend>message_generation</build_depend>

  <build_export_depend>rospy</build_export_depend>
  <build_export_depend>std_msgs</build_export_depend>
  <build_export_depend>my_custom_srv_msg_pkg</build_export_depend>
  <build_export_depend>message_runtime</build_export_depend>

  <exec_depend>rospy</exec_depend>
  <exec_depend>std_msgs</exec_depend>
  <exec_depend>my_custom_srv_msg_pkg</exec_depend>
  <exec_depend>message_runtime</exec_depend>
  

  <!-- The export tag contains other, unspecified, tags -->
  <export>
    <!-- Other tools can request additional information be placed here -->

  </export>
</package>

Everything should now work fine.

Regards,
Girish

24

@IdrisOm ,

Final words, you must pay attention to what you are doing throughout the tutorial.

You said you created my_custom_srv_msg_pkg from scratch for more than 3 times, but all of them were created wrong.

Also follow the tutorial properly. You tried to include all scripts in one single package instead of dedicated individual packages for each exercise.
You are not too far in the exercises, take time to recreate all files as mentioned in the tutorial so it helps you!

So that’s all ! Just focus more when you learn !

Best Regards,
Girish

25

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