QML Loader for variables ??

mtaylor

Trying to use a Loader to reload a variable every hour...
Below is code used, getting error on property alias temp: myvar.temp
ERROR ->Invalid alias reference. Unable to find id "myvar"

why is the Loader variable not seen?
any advice appreciated.

QML CODE used:

temp.qml - loader file // this file is updated every hour with latest weather temp

code_text

Item {
id:myvar
property string temp : " Clear - 85°"

}

main qml file
...

code_text
```Item {
    Loader { 
        id: pageLoader 
        asynchronous: true
        source: "/run/media/hammer/Data/projects/temp.qml"
    }
    
          }
          
          Text {
            // property string temp : " Clear - 85°"
           property alias temp: myvar.temp // does not work
           property alias temp: pageLoader.temp  //also tried this same error??
           text: temp
           font.family: "Roboto"
           font.pointSize: 22
           color: "black"
       }
      }

code_text

ODБOï

hi
@mtaylor said in QML Loader for variables ??:

use a Loader to reload a variable every hour...

Loader is not used for that please see the description https://doc.qt.io/qt-5/qml-qtquick-loader.html#details

You can use QML Timer

Moisi

Any id is file scoped.

So main.qml have no idea what is myvar.

You can access to your variable via the loader item property (pageLoader.item.temp).

mtaylor

ok so that gets rid of the error using text: pageLoader.myvar.temp
but nothing shows up on screen output??

i am using qmlscene for testing is there another way to show the value of that variable?

thanks

mtaylor

@LeLev
i am working on one part at a time, trying to get loader working, then implement a timer to reload every hour, thanks i looked at docs already, but cant find an example of loading a property / variable,
seems it should be easy, but not having any luck...

Yaswanth

main.qml


Window {
    visible: true
    width: 640
    height: 480
    title: qsTr("Hello World")
    Item {
        id: item
        property alias loaderEle: pageLoader
        Loader {
            id: pageLoader
            asynchronous: true
            source: "qrc:/temp.qml"
        }
    }

    Text {
        property alias temp2: item.loaderEle 
        text: temp2.item == null ? "" : temp2.item.temp
        font.family: "Roboto"
        font.pointSize: 22
        color: "black"
    }
}

temp.qml

import QtQuick 2.0

Item {
    id:myvar
    property string temp : " Clear - 85°"
}

Please make sure you have access to loader element. After that to access the properties from the loaded source in loader, use ".item"

mtaylor

@Yaswanth
still get no output..

what i did get working is this ...
some how u can call files in the same directory so i tried this
created a file called Temp.qml

import QtQuick 2.0
Item {
    id:myvar
property string temp : " Clear - 85°"
Text {
       text: temp
       font.family: "Roboto"
        font.pointSize: 22
        color: "black"
        antialiasing : true
      }
}

in main.qml
```...
Temp {width:140;height:16;anchors.right: parent} // function call to Temp.qml

works, but when i add a timer

code_text
```
Timer {
        interval: 5000 //5 sec //testing
        repeat: true
       running: true
       triggeredOnStart: true
       onTriggered: Temp {width:140;height:16;anchors.right: parent} // function call to Temp.qml
   }

get this error -
Cannot assign object type Temp_QMLTYPE_7 with no default method

how can i call this Temp.qml function with a timer?

thanks

Yaswanth

@mtaylor said in QML Loader for variables ??:

how can i call this Temp.qml function with a timer?

What do you mean by calling Temp.qml?

mtaylor

@Yaswanth
for the timer trigger -
onTriggered: Temp {width:140;height:16;anchors.right: parent} // function call to Temp.qml

am i right with the timer, that it executes that trigger line every 5 secs?

without the timer the Temp {} function works fine...

Yaswanth

@mtaylor
The way which you have used onTriggered is incorrect.
If you want to display or update Temp.qml properties, using id of the Temp.qml component, you can access.
If you want to create Temp.qml,
https://doc.qt.io/qt-5/qtqml-javascript-dynamicobjectcreation.html.
To understand Timer usage, please check https://doc.qt.io/archives/qt-4.8/qml-timer.html#onTriggered-signal

mtaylor

@Yaswanth
thanks i have read the docs,
still not clear on what can executed with the timer trigger is reached??
i am not updating Temp.qml, with qml code
it is written by a separate JS script every hour...i want my main qml file to reload that file every hour to reflect the updated variable contents

here is what i am trying to create - https://imgur.com/sAW05ez
custom kscreenlocker app to show temperature and other items

i can load the Temp.qml file by this Temp {} works fine in my test case

but when i add the timer part with Temp {}

onTriggered: Temp {width:140;height:16;anchors.right: parent} // function call to Temp.qml

get this error -
Cannot assign object type Temp_QMLTYPE_7 with no default method

i guess the question is how do make this call with a timer?

jsulm

@mtaylor said in QML Loader for variables ??:

onTriggered: Temp {width:140;height:16;anchors.right: parent}

I'm not a QML expert, but don't you create an instance of Temp here instead of calling a method on existing instance?
onTriggered expects something executable, not just an instance (without default method, so it can't be called).

Don't you actually want to update an existing Temp instance? You should have one in the same QML file where onTrigger is.

mtaylor

@jsulm
i believe i am in over my head here...i think what i am trying to do is not even possible...
kscreenlocker does not allow internet access, and i think my idea of reloading a qml page every hour will not work due to the way kscreenlocker works.

thanks for the help

ODБOï

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