Error on compiling the QDbus Server application? - c++

Question

I am new to Dbus, and off course QDBUS. I am trying to replicate the example from the nokia developer -QT forum. I have a xml file, through which I have generated the qdbus interface adaptor.cpp and .h. Now, I am trying to include this file, and build it. However, I get the compilation error. Can you please him to fix this one?
(.text.startup+0x4c):-1: error: undefined reference to `MyDemo::MyDemo(QObject*)'
generated- adaptor.cpp
/*
* This file was generated by qdbusxml2cpp version 0.7
* Command line was: qdbusxml2cpp -c DemoIfAdaptor -a demoifadaptor.h:demoifadaptor.cpp com.nokia.Demo.xml
*
* qdbusxml2cpp is Copyright (C) 2012 Digia Plc and/or its subsidiary(-ies).
*
* This is an auto-generated file.
* Do not edit! All changes made to it will be lost.
*/
#include "demoifadaptor.h"
#include <QtCore/QMetaObject>
#include <QtCore/QByteArray>
#include <QtCore/QList>
#include <QtCore/QMap>
#include <QtCore/QString>
#include <QtCore/QStringList>
#include <QtCore/QVariant>
/*
* Implementation of adaptor class DemoIfAdaptor
*/
DemoIfAdaptor::DemoIfAdaptor(QObject *parent)
: QDBusAbstractAdaptor(parent)
{
// constructor
setAutoRelaySignals(true);
}
DemoIfAdaptor::~DemoIfAdaptor()
{
// destructor
}
void DemoIfAdaptor::SayBye()
{
// handle method call com.nokia.Demo.SayBye
QMetaObject::invokeMethod(parent(), "SayBye");
}
void DemoIfAdaptor::SayHello(const QString &name, const QVariantMap &customdata)
{
// handle method call com.nokia.Demo.SayHello
QMetaObject::invokeMethod(parent(), "SayHello", Q_ARG(QString, name), Q_ARG(QVariantMap, customdata));
}
Generated Adaptor.h
/*
* This file was generated by qdbusxml2cpp version 0.7
* Command line was: qdbusxml2cpp -c DemoIfAdaptor -a demoifadaptor.h:demoifadaptor.cpp com.nokia.Demo.xml
*
* qdbusxml2cpp is Copyright (C) 2012 Digia Plc and/or its subsidiary(-ies).
*
* This is an auto-generated file.
* This file may have been hand-edited. Look for HAND-EDIT comments
* before re-generating it.
*/
#ifndef DEMOIFADAPTOR_H_1392803889
#define DEMOIFADAPTOR_H_1392803889
#include <QtCore/QObject>
#include <QtDBus/QtDBus>
class QByteArray;
template<class T> class QList;
template<class Key, class Value> class QMap;
class QString;
class QStringList;
class QVariant;
/*
* Adaptor class for interface com.nokia.Demo
*/
class DemoIfAdaptor: public QDBusAbstractAdaptor
{
Q_OBJECT
Q_CLASSINFO("D-Bus Interface", "com.nokia.Demo")
Q_CLASSINFO("D-Bus Introspection", ""
" <interface name=\"com.nokia.Demo\">\n"
" <method name=\"SayHello\">\n"
" <annotation value=\"QVariantMap\" name=\"com.trolltech.QtDBus.QtTypeName.In1\"/>\n"
" <arg direction=\"in\" type=\"s\" name=\"name\"/>\n"
" <arg direction=\"in\" type=\"a{sv}\" name=\"customdata\"/>\n"
" </method>\n"
" <method name=\"SayBye\"/>\n"
" <signal name=\"LateEvent\">\n"
" <arg direction=\"out\" type=\"s\" name=\"eventkind\"/>\n"
" </signal>\n"
" </interface>\n"
"")
public:
DemoIfAdaptor(QObject *parent);
virtual ~DemoIfAdaptor();
public: // PROPERTIES
public Q_SLOTS: // METHODS
void SayBye();
void SayHello(const QString &name, const QVariantMap &customdata);
Q_SIGNALS: // SIGNALS
void LateEvent(const QString &eventkind);
};
#endif
main.cpp file -
#include <QtCore/QCoreApplication>
#include <QVariant>
#include <QDBusAbstractInterface>
#include "demoifadaptor.h"
class MyDemo : public QObject
{
Q_OBJECT
public:
explicit MyDemo(QObject *parent = 0);
public Q_SLOTS:
void SayBye();
void SayHello(const QString &name, const QVariantMap &customdata);
Q_SIGNALS:
void LateEvent(const QString &eventkind);
};
int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);
MyDemo* demo = new MyDemo;
new DemoIfAdaptor(demo);
QDBusConnection connection = QDBusConnection::sessionBus();
bool ret = connection.registerService("com.nokia.Demo");
ret = connection.registerObject("/", demo);
return a.exec();
}
MyDemo.pro file.
#-------------------------------------------------
#
# Project created by QtCreator 2014-02-19T15:30:36
#
#-------------------------------------------------
QT += core
QT -= gui
QT += dbus
TARGET = MyDemo
CONFIG += console
CONFIG -= app_bundle
TEMPLATE = app
SOURCES += main.cpp \
demoifadaptor.cpp
HEADERS += \
demoifadaptor.h

Answer 1

Your example presents a declaration of explicit MyDemo(QObject *parent = 0); but doesn't supply it's definition. Thus the linker error. The rest of MyDemo methods must be defined as well.
You also need to run the Meta Object Compiler on the source file to avoid
"vtable..."
errors. Try re-run qmake. Any time you add a new call to the Q_OBJECT macro, you need to run qmake again. The vtables issue you're referring to in comments is directly related to that.
In case error still persist add #include "MyDemo.moc" at the end of main.cpp