qml function in Qt6

MScottM

So I've been porting one of my older programs into Qt6 and I've been getting things working so far, but I am struggling with a function that I had to get help with a while back:

https://forum.qt.io/topic/104946/qstringlist-in-qml/15.

This was able to make a QStringList accessible to my QML function so I could assign text to a bunch of labels.

Here is the QML function:

Item {
        id: readlistValues
        function readValues(anArray) {
            for (var i=0; i<33; i++)                
                //console.log("list: ", anArray[i])
                label0Text = anArray[0]
               //snip...
                label33Text = anArray[33]
        }
    }

Now when this function is called, I get the error: "Error: Cannot assign [undefined] to QString".

To make things REALLY strange - when I change the Connection{} that calls this function from the Qt6 version to the deprecated version, it works (my label text's are populated), but I get the message:

"Parameter "lblMsg" is not declared. Injection of parameters into signal handlers is deprecated. Use JavaScript functions with formal parameters instead."

    // Deprecated
    Connections {
        target: modfinder
        onSetModule: {
            modFinder.setModule(lblMsg)
        }
    }

//    Connections {
//        target: modFinder
//        function onSetModule(lblMsg) {
//            modFinder.setModule(lblMsg)
//        }
//    }

Any help appreciated!

MScottM

Okay, got it.

Per this StackExchange answer, and this Qt page, the following is an accepted way to do what I need:

onSetModule: lblMsg => modFinder.setModule(lblMsg)

Anyway, it works and clears up the warnings.

kshegunov

@MScottM said in qml function in Qt6:

Item {
        id: readlistValues
        function readValues(anArray) {
            for (var i=0; i<33; i++)                
                //console.log("list: ", anArray[i])
                label0Text = anArray[0]
               //snip...
                label33Text = anArray[33]
        }
    }

anArray[33]? Are you sure you have so many elements? Also I'd very much question the wisdom of having a million of these things: labelXXXText.

"Parameter "lblMsg" is not declared. Injection of parameters into signal handlers is deprecated. Use JavaScript functions with formal parameters instead."
    Connections {
        target: modfinder
        onSetModule: {
            modFinder.setModule(lblMsg)
        }
    }

modFinder vs modfinder, also lblMsg isn't defined, specify explicitly through an object id. Is this property part of the target? Perhaps it's supposed to be:

modFinder.setModule(modFinder.lblMsg)

MScottM

Hello @kshegunov, thank you for taking a look! To your question about if I'm sure about the number of elements, yes, there are exactly 33 labels that I set with different information when ever a particular GUI element is clicked. The text for the elements are read from a configuration file that I can change whenever something in the system changes.

Having said that, I do this kind of thing as a challenge to learn and increase my skill - I would consider myself an advanced beginner. If you can suggest a better way to do this, I will happily listen! This was one of the trickiest parts of the program and I remember spending quite a bit of time figuring out how to get it working.

So here is something really strange: the deprecated Connection that you show above is the one that works, and I never noticed the issue with the (non)capitalized name. If I change it to modFinder, it stops working. I have that defined in my main.cpp:

moduleFinder modFinder;

If I change the new version to match, it still doesn't work (crashes after "ReferenceError: modfinder is not defined")

    Connections {
        target: modfinder //changed from modFinder
        function onSetModule(lblMsg) {
            modFinder.setModule(modFinder.lblMsg)
        }
    }

MScottM

Okay, got it.

Per this StackExchange answer, and this Qt page, the following is an accepted way to do what I need:

onSetModule: lblMsg => modFinder.setModule(lblMsg)

Anyway, it works and clears up the warnings.