Qt GRPC: Why is handling a response required for a grpc call?

spyropoulosamandad

I've recently been working with Qt Grpc in 6.8.1 in C++, following along the Client Guide Example:

std::unique_ptr<QGrpcCallReply> reply = m_client.UnaryCall(requestMessage);
const auto *replyPtr = reply.get(); // 1
QObject::connect(
    replyPtr, &QGrpcCallReply::finished, replyPtr,
    [reply = std::move(reply)](const QGrpcStatus &status) {
        ...
    },
    Qt::SingleShotConnection        // 2
);

I was able to get the example to work. However, I noticed that if I omitted the code which handles the response, my server would not receive any call. Specifically, just

std::unique_ptr<QGrpcCallReply> reply = m_client.UnaryCall(requestMessage);

would not execute a grpc call that my server received. Why? In the full example above, does the call get executed when QObject::connect is called?

I understand that the vast majority of the time, we need to check the response to gain information so this is an edge case. I am curious why the code didn't behave as I expected.

Christian Ehrlicher

std::unique_ptr<QGrpcCallReply> reply = m_client.UnaryCall(requestMessage);

I would guess you should think about how long this object is alive.