Unable to declare parameter that are only known at runtime

[saikishor]

Hello!

I'm currently facing an issue with the ros2 parameters. I'm not sure how to approach this, from Iron on ros2_controller creates a node without the node options allow_undeclared_parameters and automatically_declare_parameters_from_overrides. I would like to define a block of parameters for my controller, however, their namespace is only known at the runtime. This is making it hard for me to load the parameters using the spawner.

A simple case would be something like below:

joints: ["joint_1", "joint_2"]
parameters:
  joint_1:
    type: rotary
    frame: joint_1_link
  joint_2:
    type: rotary
    frame: joint_2_link

To parse such a block, we need to know the joints parameter already at the time of declaration, and this is currently not possible. So, at the time of declaration, as this is not known, I'm not able to declare the parameter block and hence unable to set any of the respective parameters.

std::vector<JointParams> joint_params;
auto joint_names = node->declare_parameter<std::vector<std::string>>("joints", std::vector<std::string>());
for (auto joint : joint_names)
{
  RCLCPP_INFO(logger, "Adding Joint: %s", joint.c_str());
  JointParams params;
  params.name = name;
  params.type = node->declare_parameter<std::string>("parameters." + name + ".type", std::string());
  params.frame = node->declare_parameter<std::string>("parameters." + name + ".frame", std::string());
  params.param_name = node->declare_parameter<std::string>(name + ".param_name", std::string());
  joint_params.push_back(params);
}

Moreover, in the existing parameter callbacks(add_pre_set_parameters_callback , add_on_set_parameters_callback , and add_post_set_parameters_callback), we cannot declare or set any parameters, so I would like to know if there is a way to declare some parameters at runtime. If not, I propose to have a new callback method that helps to declare the parameters at runtime or a way to specify to allow undeclared parameters to a specific namespace.

Is there a better way to approach this problem?

[saikishor]

Hello!

Can someone help me with this?. I would like to know how to handle this, so I can fix it at different places of ros2_control. Any help is appreciated.

Thank you,

[saikishor]

This solves the issue by setting the arguments in the NodeOptions. Please refer to ros-controls/ros2_control#1293