View Full Version : DBus adaptor and 'const QDBusMessege &messege' argument.

8th February 2011, 16:18

In documentation of DBus in qt: Declaring Slots in D-Bus Adaptors (http://doc.trolltech.com/latest/qdbusdeclaringslots.html) information about QDBusMessage parameter can be found.

I need access to this parameter to be able post errors instead standard output.
According to this documentation it should look like this (more or less):

class SomeAdaptor : public: QDBusAbstractAdaptor
Q_CLASSINFO("D-Bus Interface", "org.some.dbus.iterface.name")
Q_CLASSINFO("D-Bus Introspection", ""
" <interface name=\"org.some.dbus.iterface.name\">\n"
" <method name=\"myMethod\">\n"
" <arg direction=\"in\" type=\"u\" name=\"in\"/>\n"
" <arg direction=\"out\" type=\"b\" name=\"out1\"/>\n"
" <arg direction=\"out\" type=\"s\" name=\"out2\"/>\n"
" </method>\n"

.... // standard stuff

public Q_SLOTS:
bool myMethod(uint in, QString &out2); // this version works
bool myMethod(uint in, const QDBusMessege &messege, QString &out2); // this version doesn't work
First version of myMethod slot works perfectly! Data are received and send back.
But when this method is replaced with second version, it doesn't work (client is unable to call method).
Now what should I do to make it work?
Should I correct xml data in Q_CLASSINFO("D-Bus Introspection"? If yes, than how?
Or maybe my declaration of slot is incorrect?
Documentations says that this argument should be between input and output arguments like in my example.

9th February 2011, 10:57
Update: I've also tried:

bool myMethod(uint in, QDBusMessege &messege, QString &out2);
bool myMethod(uint in, QString &out2, const QDBusMessege &messege);
bool myMethod(uint in, QString &out2, QDBusMessege &messege);
but it doesn't work either.

11th February 2011, 09:15

I've checked all classes related with DBus and I've found nice clear solution, much better than this extra argument. There is class QDBusContext (http://doc.trolltech.com/latest/qdbuscontext.html) which is used like this:

class ActualDBusObjectNotAdaptor : public QObject, protected QDBusContext {
// rest is the same

bool ActualDBusObjectNotAdaptor::myMethod(uint in, QString &out2) {
if (in<0) {
sendErrorReply("Error.string", "User readable messege");
So extra parameter is not needed.
Apparently here in documentations (http://doc.trolltech.com/latest/qdbusdeclaringslots.html) is mistake (it doesn't work as specified) probably some leftover after older version or at least it is incomplete.