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ROS Service global name not defined

asked 2019-01-18 10:58:41 -0500

Jägermeister gravatar image

updated 2019-01-18 11:14:06 -0500

I am trying to make my node a ROS service which gets triggered when it receives boolean value of true, thus I have added the following to its constructor:

self.imgproc_srv = rospy.Service("/perception/request_detection", RequestDetection, self.detection_processor_srv)

here is the callback:

def detection_processor_srv(self, req): 
         print("It works!")

And of course, I have the file RequestDetection.srv as:

bool detection_requested # our trigger to initiate the visual detection

and I imported this in my script as:

from common.srv import *

which is where I plan to keep the services.

Needless to say, I did catkin_make as well, after all this.

Yet I receive:

NameError: global name 'RequestDetection' is not defined

What am I doing wrong?

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answered 2019-01-18 11:12:08 -0500

It looks like you haven't defined your service properly, I would have expected you to get an error when you try and catkin_make this.

If you look at the tutorial on messages and services, you can see that a service needs to define both the request and response parts separated by there hyphens --- like the example shown there:

int64 a
int64 b
int64 sum

As also described in the tutorial above you need to setup your CMakeLists.txt file to make sure that this service is built too.

Hope this helps.

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If I only want to call this service and not expect anything in return, the parts above --- are not required, right? I noticed since I won't expect anything, it should now work as it is like in my code?

EDIT: It was the CMakeLists.txt ,now it works.

Jägermeister gravatar image Jägermeister  ( 2019-01-18 11:13:21 -0500 )edit

I see. Glad you got this working.

PeteBlackerThe3rd gravatar image PeteBlackerThe3rd  ( 2019-01-18 12:33:25 -0500 )edit

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Asked: 2019-01-18 10:58:41 -0500

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Last updated: Jan 18 '19