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Ros2 Foxy Python custom SRV type error

asked 2021-07-23 10:26:01 -0500

maxunm gravatar image

Here's the traceback from the error,

[Intersection(i_d=0, ins=[1011, 1804], out=[1000], clear=True), Intersection(i_d=1, ins=[1103, 1001], out=[1002], clear=True), Intersection(i_d=2, ins=[1002, 1008], out=[1004, 1010], clear=True)]
[INFO] [1627053698.780029518] [intersection_action_server]: Checking intersection
[INFO] [1627053698.780460999] [intersection_action_server]: Incoming request
Type: Incoming RFID: 1002
[INFO] [1627053698.780763667] [intersection_action_server]: Sending back: Clear
[INFO] [1627053053.366115161] [intersection_action_server]: Checking intersection
[INFO] [1627053053.366806566] [intersection_action_server]: Incoming request
Type: Incoming RFID: 1002
[INFO] [1627053053.367215310] [intersection_action_server]: Sending back: Clear
Traceback (most recent call last):
File "/home/mrumel/fisher_agc/AGCROS/install/server/lib/server/intersection_manager", line 11, in <module>
load_entry_point('server==0.0.0', 'console_scripts', 'intersection_manager')()
File "/home/mrumel/fisher_agc/AGCROS/install/server/lib/python3.8/site-packages/server/", line 70, in main
File "/opt/ros/foxy/lib/python3.8/site-packages/rclpy/", line 191, in spin
File "/opt/ros/foxy/lib/python3.8/site-packages/rclpy/", line 711, in spin_once
raise handler.exception()
File "/opt/ros/foxy/lib/python3.8/site-packages/rclpy/", line 239, in __call__
File "/opt/ros/foxy/lib/python3.8/site-packages/rclpy/", line 426, in handler
await call_coroutine(entity, arg)
File "/opt/ros/foxy/lib/python3.8/site-packages/rclpy/", line 381, in _execute_service
srv.send_response(response, header)
File "/opt/ros/foxy/lib/python3.8/site-packages/rclpy/", line 72, in send_response
raise TypeError()

Here's my .SRV file first, it's filename is IntersectionManager.srv

string ask
string is_clear

My Service node

import rclpy
from rclpy.node import Node
from agc_interfaces.srv import IntersectionManager
from dataclasses import dataclass
from typing import Optional, List
import json
import ast

class Intersection:
    i_d: int
    ins: List[int]
    out: List[int]
    clear: bool

intersectionList: List[Intersection] = []

class IntersectionActionServer(Node):

    def __init__(self):
        self.srv = self.create_service(IntersectionManager,'intersection_manage',self.execute_callback)
        global intersectionList
        with open('/home/maxunm/fisher_agc/AGCROS/scs_rfids.json') as f: 
            data = json.load(f)
        dicts = data['rfids'] #Extract all the RFIDs from data
        i = 0
        for rfid in dicts:
            for s in rfid['args']:
                if "intr" in s:
                    split_s = s.split(';',-1)
                    ins = ast.literal_eval(split_s[1])
                    out = ast.literal_eval(split_s[2])
                    i = i+1

    def execute_callback(self, request, responce): 
        self.get_logger().info('Checking intersection')
        ask_list = request.ask.split(",")
        which = ask_list[0]
        rfid_num  = int(ask_list[1])
        self.get_logger().info('Incoming request\nType: %s RFID: %d' % (which, rfid_num))
        for intersect in intersectionList:
            if which == "Incoming": #AGV coming into an intersection
                if rfid_num in intersect.ins: #Which intersection the rfid it's at is in
                    """Check for if that intersection is locked or not"""
                    if intersect.clear:
                        responce.is_clear = str('Clear')
                        intersect.clear = False
                        responce.is_clear = str('Blocked')
            else: #AGV leaving intersection
                if rfid_num in intersect.out:
                    if intersect.clear:
                        responce.is_clear = str('ERROR')
                        intersect.clear = True
                        responce.is_clear = str('OK')
                        intersect.clear = True
        self.get_logger().info('Sending back: %s'%(responce ...
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1 Answer

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answered 2021-07-23 10:35:13 -0500

Ranjit Kathiriya gravatar image

updated 2021-07-23 10:35:45 -0500

File "/opt/ros/foxy/lib/python3.8/site-packages/rclpy/", line 72, in send_response - raise TypeError() - TypeError

The issue is with your service code in the execute_callback() function. The return is there but you have not defined the variable. In other words, it is returning nothing but in your service file, you have stated that it is returning a string.

return <your return string>

Just make that change in your service code > execute_callback() function.

Hope it helps you. feel free to drop a comment if it is not working.

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Oh my gosh, I cant believe I forgot to return the response. Thank you for your help

maxunm gravatar image maxunm  ( 2021-07-23 10:37:57 -0500 )edit

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Asked: 2021-07-23 10:26:01 -0500

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Last updated: Jul 23 '21