Confusion about ROS2 parameters in MATLAB Coder

Hello everyone,

my confusion stems from the fact, that is seems not be possible to get array-valued parameters from a node. I use the following MWE-node which gets code generated with MATLAB Coder (codegen).

function myNode() %#codegen

nodeParams.gains = [0.5, 1.0, 2.0];

node = ros2node("/my_node", Parameters=nodeParams);

r = ros2rate(node, 10);

while true

[gains, ok] = getParameter(node, "gains", Datatype="double");

if ok

fprintf("First gain: %f\n", gains(1));

else

fprintf("Status is false\n");

end

waitfor(r);

end

end

This will successfully generate code, which can be compiled into a standlaone ROS2 node. Analyzing the node:

name@host:~/ros_ws$ ros2 param get /my_node gains

Double values are: [0.5, 1.0, 2.0]

Which means, that the parameter is set correct. But the node will repeatedly print:

Status is false

The code generation will also fail when actively trying to index into gains(2). I see from the Simulink-Coder documentation that there you are able to specify the datatype="double[]" which would make it clear that i want to read an array of doubles. But this is not allowed for the getParameter method. Does this mean, that it is simply not possible?

I am looking for some clarification on this topic, or possible workarounds. Thank you :)