Getting UINT16 param from ArduPilot doesn't work

[pavloblindnology]

Cannot read any param from ArduPilot other than float and int32 - say RC1_MIN (int16).
Aftere debugging I can see that the problem is in mavlink_parameter_client::get_param_async_typesafe function.
Before it parameter is succesfully read. But checking its type (int16_t vs int32_t) doesn't pass here

MAVSDK/src/mavsdk/core/mavlink_parameter_client.cpp

Line 280 in b4160bb

if (value.is<T>()) {

[julianoes]

Does ArduPilot use uint16 params? Could you help me reproduce the issue?

[pavloblindnology]

Does ArduPilot use uint16 params? Could you help me reproduce the issue?

No, AP supports only int8, int16, int32 and float params.
To reproduce the bug just try to read any int16 param (say RC1_MIN) with any get_param_int method (say mavsdk::Param::get_param_int).

I've fixed this by specializing template method MavlinkParameterClient::get_param_async_typesafe like this

template<>
void MavlinkParameterClient::get_param_async_typesafe(
    const std::string& name, const GetParamTypesafeCallback<int32_t> callback, const void* cookie)
{
    // We need to delay the type checking until we get a response from the server.
    GetParamAnyCallback callback_future_result = [callback](Result result, ParamValue value) {
        if (result == Result::Success) {
            if (value.is<int32_t>()) {
                callback(Result::Success, value.get<int32_t>());
            } else if (value.is<int16_t>()) {
                callback(Result::Success, value.get<int16_t>());
            } else if (value.is<int8_t>()) {
                callback(Result::Success, value.get<int8_t>());
            } else {
                callback(Result::WrongType, {});
            }
        } else {
            callback(result, {});
        }
    };
    get_param_async(name, callback_future_result, cookie);
}

[julianoes]

Given you have code to fix it @pavloblindnology, do you want to create a pull request to contribute it? That would be great.

[pavloblindnology]

Sure, why not. If it looks plausible to you.

[pavloblindnology]

@julianoes Access denied while pushing PR branch.

[JonasVautherin]

@pavloblindnology: you need to create a fork, push your branch to your fork, and open a PR to this repo 👍

[pavloblindnology]

@JonasVautherin Please note that I also created backport v2.12 PR #2401.