class QDBusContext#

The QDBusContext class allows slots to determine the D-Bus context of the calls. More…

Synopsis#

Methods#

Note

This documentation may contain snippets that were automatically translated from C++ to Python. We always welcome contributions to the snippet translation. If you see an issue with the translation, you can also let us know by creating a ticket on https:/bugreports.qt.io/projects/PYSIDE

Detailed Description#

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

When a slot is called in an object due to a signal delivery or due to a remote method call, it is sometimes necessary to know the context in which that happened. In particular, if the slot determines that it wants to send the reply at a later opportunity or if it wants to reply with an error, the context is needed.

The QDBusContext class is an alternative to accessing the context that doesn’t involve modifying the code generated by the Qt D-Bus XML compiler (qdbusxml2cpp) .

QDBusContext is used by subclassing it from the objects being exported using registerObject() . The following example illustrates the usage:

class MyObject(QObject,
                protected QDBusContext

    Q_OBJECT
    conn = QDBusConnection()
    msg = QDBusMessage()
    #...
# protected slots
    def process():
# public slots
    def methodWithError():
    methodWithDelayedReply = QString()

def methodWithError(self):

    sendErrorReply(QDBusError.NotSupported,
                   "The method call 'methodWithError()' is not supported")

def methodWithDelayedReply(self):

    conn = connection()
    msg = message()
    setDelayedReply(True)
    QMetaObject::invokeMethod(self.process, Qt::QueuedConnection)
    return QString()

The example illustrates the two typical uses, that of sending error replies and that of delayed replies.

Note: do not subclass QDBusContext and QDBusAbstractAdaptor at the same time. QDBusContext should appear in the real object, not the adaptor. If it’s necessary from the adaptor code to determine the context, use a public inheritance and access the functions via QObject::parent().

__init__()#

Constructs an empty QDBusContext .

calledFromDBus()#
Return type:

bool

Returns true if we are processing a D-Bus call. If this function returns true, the rest of the functions in this class are available.

Accessing those functions when this function returns false is undefined and may lead to crashes.

connection()#
Return type:

QDBusConnection

Returns the connection from which this call was received.

isDelayedReply()#
Return type:

bool

Returns true if this call will have a delayed reply.

message()#
Return type:

QDBusMessage

Returns the message that generated this call.

sendErrorReply(type[, msg=""])#
Parameters:

This is an overloaded function.

Sends an error type as a reply to the caller. The optional msg parameter is a human-readable text explaining the failure.

If an error is sent, the return value and any output parameters from the called slot will be ignored by Qt D-Bus.

sendErrorReply(name[, msg=""])
Parameters:

  • name – str

  • msg – str

Sends an error name as a reply to the caller. The optional msg parameter is a human-readable text explaining the failure.

If an error is sent, the return value and any output parameters from the called slot will be ignored by Qt D-Bus.

setDelayedReply(enable)#
Parameters:

enable – bool

Sets whether this call will have a delayed reply or not.

If enable is false, Qt D-Bus will automatically generate a reply back to the caller, if needed, as soon as the called slot returns.

If enable is true, Qt D-Bus will not generate automatic replies. It will also ignore the return value from the slot and any output parameters. Instead, the called object is responsible for storing the incoming message and send a reply or error at a later time.

Failing to send a reply will result in an automatic timeout error being generated by D-Bus.

See also

isDelayedReply()