QHttpServer Class

QHttpServer is a simplified API for QAbstractHttpServer and QHttpServerRouter. More...

Header: #include <QHttpServer>
CMake: find_package(Qt6 REQUIRED COMPONENTS HttpServer)
target_link_libraries(mytarget PRIVATE Qt6::HttpServer)
qmake: QT += httpserver
Since: Qt 6.4
Inherits: QAbstractHttpServer
Status: Technical Preview

Public Types

Public Functions

QHttpServer(QObject *parent = nullptr)
virtual ~QHttpServer()
void afterRequest(ViewHandler &&viewHandler)
bool route(Args &&... args)
QHttpServerRouter *router()
void setMissingHandler(QHttpServer::MissingHandler handler)

Detailed Description

QHttpServer server;

server.route("/", [] () {
    return "hello world";
});
server.listen();

Member Type Documentation

[alias] QHttpServer::MissingHandler

Type alias for std::function<void(const QHttpServerRequest &request, QHttpServerResponder &&responder)>.

Member Function Documentation

[explicit] QHttpServer::QHttpServer(QObject *parent = nullptr)

Creates an instance of QHttpServer with parent parent.

[virtual noexcept] QHttpServer::~QHttpServer()

Destroys a QHttpServer.

template <typename ViewHandler> void QHttpServer::afterRequest(ViewHandler &&viewHandler)

Register a function to be run after each request.

The viewHandler argument can be a function pointer, non-mutable lambda, or any other copiable callable with const call operator. The callable can take one or two optional arguments: QHttpServerResponse && and const QHttpServerRequest &. If both are given, they can be in either order.

Examples:

QHttpServer server;

// Valid:
server.afterRequest([] (QHttpServerResponse &&resp, const QHttpServerRequest &request) {
    return std::move(resp);
}
server.afterRequest([] (const QHttpServerRequest &request, QHttpServerResponse &&resp) {
    return std::move(resp);
}
server.afterRequest([] (QHttpServerResponse &&resp) { return std::move(resp); }

// Invalid (compile time error):
// resp must be passed by universal reference
server.afterRequest([] (QHttpServerResponse &resp, const QHttpServerRequest &request) {
    return std::move(resp);
}
// request must be passed by const reference
server.afterRequest([] (QHttpServerResponse &&resp, QHttpServerRequest &request) {
    return std::move(resp);
}

template <typename Rule = QHttpServerRouterRule, typename... Args> bool QHttpServer::route(Args &&... args)

This function is just a wrapper to simplify the router API.

This function takes variadic arguments args. The last argument is a callback (ViewHandler). The remaining arguments are used to create a new Rule (the default is QHttpServerRouterRule). This is in turn added to the QHttpServerRouter. It returns true if a new rule is created, otherwise it returns false. This function must not be called from a callback (ViewHandler).

ViewHandler can be a function pointer, non-mutable lambda, or any other copiable callable with const call operator. The callable can take two optional special arguments: const QHttpServerRequest& and QHttpServerResponder&&. These special arguments must be the last in the parameter list, but in any order, and there can be none, one, or both of them present. Only handlers with void return type can accept QHttpServerResponder&& arguments.

Examples:

QHttpServer server;

// Valid:
server.route("test", [] (const int page) { return ""; });
server.route("test", [] (const int page, const QHttpServerRequest &request) { return ""; });
server.route("test", [] (QHttpServerResponder &&responder) { return ""; });

// Invalid (compile time error):
server.route("test", [] (const QHttpServerRequest &request, const int page) { return ""; }); // request must be last
server.route("test", [] (QHttpServerRequest &request) { return ""; });      // request must be passed by const reference
server.route("test", [] (QHttpServerResponder &responder) { return ""; });  // responder must be passed by universal reference

Requests are processed sequentially inside the QHttpServer's thread by default. The request handler may return QFuture<QHttpServerResponse> if asynchronous processing is desired:

server.route("/feature/", [] (int id) {
    return QtConcurrent::run([] () {
        return QHttpServerResponse("the future is coming");
    });
});

The body of QFuture is executed asynchronously, but all the network communication is executed sequentially. QHttpServerResponder&& special argument is not available for routes returning a QFuture.

See also QHttpServerRouter::addRule.

QHttpServerRouter *QHttpServer::router()

Returns the router object.

void QHttpServer::setMissingHandler(QHttpServer::MissingHandler handler)

Set a handler to call for unhandled paths.

The invocable passed as handler will be invoked for each request that cannot be handled by any of registered route handlers. Passing a default-constructed std::function resets the handler to the default one that produces replies with status 404 Not Found.

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