Signal in QML becomes undefined

SietseAchterop

Hello list,

In my pyqt5 QML-app (5.15.2) I am struggling get rid of the deprecation mentioned below.
Here a very simple QML example that shows the deprecation problem.

Item {

    RowLayout {
	id: sessionId
          
	Connections {
            target: crew_mpl
            onSessionsig: {
		console.log(sessig);
	    }
	    .......
	}	   
    }
}

The target is created in my main.py:

    gd.crewPlots = CrewForm()
    gd.context.setContextProperty("crew_mpl", gd.crewPlots)

There also is the following signal:

    sessionsig = pyqtSignal(list, arguments =['sessig'])

The warning that I get is:
QML Connections: Implicitly defined onFoo properties in Connections are deprecated. Use this syntax instead: function onFoo(<arguments>) <

I try to solve this by following the advice and put my code in a different function as per another advice that I found.
I do this in 2 steps.

Item {

    RowLayout {
	id: sessionId

	function mysig (sessig) {
	    console.log(sessig);
	}

	Connections {
            target: crew_mpl
            onSessionsig: {
		mysig(sessig);
	    }}}}

This works fine, the value of sessig is printed, but when I use the new syntax: function onSessionsig () {}
Then I get the error:
qml: undefined

How can I make this work?
Thanks in advance,
Sietse

GrecKo

That's not how the new syntax work. You should put the function definition in the Connections block.

Old:

Connections {
    target: crew_mpl
    onSessionsig: {
	console.log(sessig);
    }
}

New:

Connections {
    target: crew_mpl
    function onSessionsig (session_sig) { // you can use an arbitrary parameter name, only the name of the function has to match on<SignalName>
	console.log(session_sig);
    }
}

SietseAchterop

@GrecKo Thanks, solved!
I missed that the arguments are the signals. That's what you get when you google for answers instead of properly reading the documentation....
Regards, Sietse