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QML Loader for variables ??

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  • M Offline
    M Offline
    mtaylor
    wrote on 7 Oct 2019, 18:26 last edited by
    #1

    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

    O 1 Reply Last reply 7 Oct 2019, 18:38
    0
    • M mtaylor
      7 Oct 2019, 18:26

      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

      O Offline
      O Offline
      ODБOï
      wrote on 7 Oct 2019, 18:38 last edited by
      #2

      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

      1 Reply Last reply
      1
      • M Offline
        M Offline
        Moisi
        wrote on 7 Oct 2019, 18:51 last edited by
        #3

        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).

        1 Reply Last reply
        1
        • M Offline
          M Offline
          mtaylor
          wrote on 7 Oct 2019, 19:20 last edited by
          #4

          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

          1 Reply Last reply
          0
          • M Offline
            M Offline
            mtaylor
            wrote on 7 Oct 2019, 22:18 last edited by
            #5

            @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...

            1 Reply Last reply
            0
            • Y Offline
              Y Offline
              Yaswanth
              wrote on 7 Oct 2019, 23:41 last edited by
              #6

              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"

              M 1 Reply Last reply 8 Oct 2019, 01:17
              0
              • Y Yaswanth
                7 Oct 2019, 23:41

                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"

                M Offline
                M Offline
                mtaylor
                wrote on 8 Oct 2019, 01:17 last edited by
                #7

                @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

                Y 1 Reply Last reply 8 Oct 2019, 01:19
                0
                • M mtaylor
                  8 Oct 2019, 01:17

                  @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

                  Y Offline
                  Y Offline
                  Yaswanth
                  wrote on 8 Oct 2019, 01:19 last edited by
                  #8

                  @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?

                  M 1 Reply Last reply 8 Oct 2019, 01:37
                  0
                  • Y Yaswanth
                    8 Oct 2019, 01:19

                    @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?

                    M Offline
                    M Offline
                    mtaylor
                    wrote on 8 Oct 2019, 01:37 last edited by
                    #9

                    @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...

                    Y 1 Reply Last reply 8 Oct 2019, 01:51
                    0
                    • M mtaylor
                      8 Oct 2019, 01:37

                      @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...

                      Y Offline
                      Y Offline
                      Yaswanth
                      wrote on 8 Oct 2019, 01:51 last edited by
                      #10

                      @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

                      M 1 Reply Last reply 8 Oct 2019, 02:12
                      0
                      • Y Yaswanth
                        8 Oct 2019, 01:51

                        @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

                        M Offline
                        M Offline
                        mtaylor
                        wrote on 8 Oct 2019, 02:12 last edited by
                        #11

                        @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?

                        jsulmJ 1 Reply Last reply 8 Oct 2019, 05:35
                        0
                        • M mtaylor
                          8 Oct 2019, 02:12

                          @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?

                          jsulmJ Offline
                          jsulmJ Offline
                          jsulm
                          Lifetime Qt Champion
                          wrote on 8 Oct 2019, 05:35 last edited by jsulm 10 Aug 2019, 05:35
                          #12

                          @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.

                          https://forum.qt.io/topic/113070/qt-code-of-conduct

                          M 1 Reply Last reply 11 Oct 2019, 19:46
                          0
                          • jsulmJ jsulm
                            8 Oct 2019, 05:35

                            @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.

                            M Offline
                            M Offline
                            mtaylor
                            wrote on 11 Oct 2019, 19:46 last edited by mtaylor 10 Nov 2019, 19:46
                            #13

                            @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

                            O 1 Reply Last reply 12 Oct 2019, 08:25
                            0
                            • M mtaylor
                              11 Oct 2019, 19:46

                              @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

                              O Offline
                              O Offline
                              ODБOï
                              wrote on 12 Oct 2019, 08:25 last edited by
                              #14
                              This post is deleted!
                              1 Reply Last reply
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