ros2 humble python调用ActionServer自定义goal_callback报错

[luminuo]

背景：

ros2 humble python调用ActionServer自定义goal_callback报错

问题描述：

自定义ActionServer内goal_callback，报错：AttributeError: 'Nav_Goal' object has no attribute 'request'；打印goal_handle发现它的类型是base_interfaces_demo.action._nav.Nav_Goal，而不是rclpy.action.server.ServerGoalHandle

具体细节和上下文：

接口Nav.action

float32 goal_x
float32 goal_y
float32 goal_theta
---
float32 turtle_x
float32 turtle_y
float32 turtle_theta
---
float32 distance

服务端

from rclpy.action import ActionServer
self.server = ActionServer(
            self,
            Nav,
            'nav',
            self.execute_callback,
            goal_callback=self.goal_callback,
            cancel_callback=self.cancel_callback
        )

def goal_callback(self, goal_handle):
        self.get_logger().info("*********%s"%type(goal_handle))
        # 访问目标数据
        goal = goal_handle.request

        # 检查目标的合法性
        if (goal.goal_x < 0 or goal.goal_x > 11.08 or
            goal.goal_y < 0 or goal.goal_y > 11.08):
            goal_handle.canceled()  # 取消目标
            return None  # 返回 None 表示没有接受目标

        # 目标合法，接受目标
        goal_handle.accept()
        return goal_handle  # 返回 goal_handle 以便进一步处理

报错信息

[exer03_action_server-2] [INFO] [1723443526.653815246] [exer03_action_server_node_py]: *********<class 'base_interfaces_demo.action._nav.Nav_Goal'>
[exer03_action_server-2] Traceback (most recent call last):
[exer03_action_server-2]   File "/home/ws01_plumbing/install/py07_exercise/lib/py07_exercise/exer03_action_server", line 33, in <module>
[exer03_action_server-2]     sys.exit(load_entry_point('py07-exercise==0.0.0', 'console_scripts', 'exer03_action_server')())
[exer03_action_server-2]   File "/home/ws01_plumbing/install/py07_exercise/lib/python3.10/site-packages/py07_exercise/exer03_action_server.py", line 94, in main
[exer03_action_server-2]     rclpy.spin(Exer03ActionServer())
[exer03_action_server-2]   File "/opt/ros/humble/local/lib/python3.10/dist-packages/rclpy/__init__.py", line 222, in spin
[exer03_action_server-2]     executor.spin_once()
[exer03_action_server-2]   File "/opt/ros/humble/local/lib/python3.10/dist-packages/rclpy/executors.py", line 739, in spin_once
[exer03_action_server-2]     self._spin_once_impl(timeout_sec)
[exer03_action_server-2]   File "/opt/ros/humble/local/lib/python3.10/dist-packages/rclpy/executors.py", line 736, in _spin_once_impl
[exer03_action_server-2]     raise handler.exception()
[exer03_action_server-2]   File "/opt/ros/humble/local/lib/python3.10/dist-packages/rclpy/task.py", line 239, in __call__
[exer03_action_server-2]     self._handler.send(None)
[exer03_action_server-2]   File "/opt/ros/humble/local/lib/python3.10/dist-packages/rclpy/executors.py", line 437, in handler
[exer03_action_server-2]     await call_coroutine(entity, arg)
[exer03_action_server-2]   File "/opt/ros/humble/local/lib/python3.10/dist-packages/rclpy/executors.py", line 403, in _execute_waitable
[exer03_action_server-2]     await waitable.execute(data)
[exer03_action_server-2]   File "/opt/ros/humble/local/lib/python3.10/dist-packages/rclpy/action/server.py", line 492, in execute
[exer03_action_server-2]     await self._execute_goal_request(taken_data['goal'])
[exer03_action_server-2]   File "/opt/ros/humble/local/lib/python3.10/dist-packages/rclpy/action/server.py", line 280, in _execute_goal_request
[exer03_action_server-2]     response = await await_or_execute(self._goal_callback, goal_request.goal)
[exer03_action_server-2]   File "/opt/ros/humble/local/lib/python3.10/dist-packages/rclpy/executors.py", line 107, in await_or_execute
[exer03_action_server-2]     return callback(*args)
[exer03_action_server-2]   File "/home/ws01_plumbing/install/py07_exercise/lib/python3.10/site-packages/py07_exercise/exer03_action_server.py", line 29, in goal_callback
[exer03_action_server-2]     goal = goal_handle.request
[exer03_action_server-2] AttributeError: 'Nav_Goal' object has no attribute 'request'
[ERROR] [exer03_action_server-2]: process has died [pid 16798, exit code 1, cmd '/home/ws01_plumbing/install/py07_exercise/lib/py07_exercise/exer03_action_server --ros-args'].

[小伊]

在 ROS 2 的 rclpy 框架中，当你定义一个 Action Server 的 goal_callback 时，你需要正确地处理传入的参数。在你的代码中，goal_callback 被错误地期望接收一个 ServerGoalHandle 对象，但实际上在 ROS 2 的较新版本中（包括 Humble），goal_callback 直接接收的是 Action 的目标（Goal）对象，而不是 ServerGoalHandle。

解决方案

你需要修改 goal_callback 以直接接收 Nav_Goal 类型的对象，而不是 ServerGoalHandle。同时，你需要从 goal_handle 中获取 goal 的方式需要改变，因为你现在直接处理的就是 goal 对象。

修改后的 goal_callback 应该像这样：

def goal_callback(self, goal):
    self.get_logger().info("Received goal: x={}, y={}, theta={}".format(goal.goal_x, goal.goal_y, goal.goal_theta))

    # 检查目标的合法性
    if (goal.goal_x < 0 or goal.goal_x > 11.08 or
        goal.goal_y < 0 or goal.goal_y > 11.08):
        # 这里你不需要直接调用 goal_handle.canceled()，因为在这个回调中没有 goal_handle
        # 你需要在 execute_callback 中处理取消逻辑
        return rclpy.action.GoalResponse.REJECT

    # 目标合法，返回 ACCEPT 表示接受目标
    return rclpy.action.GoalResponse.ACCEPT

注意：

1. goal_callback 现在直接接收 goal 对象。
2. goal_callback 需要返回一个 GoalResponse，而不是执行 goal_handle.accept() 或 goal_handle.canceled()。这是因为 goal_callback 是在决定是否接受或拒绝目标时调用的，而实际的处理（如接受或取消）将在 execute_callback 中进行。

完整的 Action Server 示例

这里是一个简化的 Action Server 示例，展示如何设置 goal_callback 和 execute_callback：

from rclpy.action import ActionServer, GoalResponse
from rclpy.node import Node
from your_package.action import Nav

class NavActionServer(Node):
    def __init__(self):
        super().__init__('nav_action_server')
        self.server = ActionServer(
            self,
            Nav,
            'nav',
            self.execute_callback,
            goal_callback=self.goal_callback,
            cancel_callback=self.cancel_callback
        )

    def goal_callback(self, goal):
        # 检查目标合法性
        if (goal.goal_x < 0 or goal.goal_x > 11.08 or
            goal.goal_y < 0 or goal.goal_y > 11.08):
            return GoalResponse.REJECT
        return GoalResponse.ACCEPT

    def execute_callback(self, goal_handle):
        self.get_logger().info('Executing goal...')
        # 这里是实际执行目标的地方
        # 假设执行成功
        result = Nav.Result()
        result.distance = 10.0  # 假设的距离
        goal_handle.succeed(result)

    def cancel_callback(self, goal_handle):
        self.get_logger().info('Goal canceled')
        goal_handle.canceled()

def main(args=None):
    rclpy.init(args=args)
    nav_server = NavActionServer()
    rclpy.spin(nav_server)
    nav_server.destroy_node()
    rclpy.shutdown()

if __name__ == '__main__':
    main()

注意：你需要根据你的具体包名和命名空间调整代码中的 from your_package.action import Nav。

---

以上为生成回答，仅供参考～

[小鱼]

@luminuo 提供下完整代码，看不太懂

[luminuo]

@小鱼 按上面那个回复解决了，但是要怎么把未解决改成已解决