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How to create QML singleton

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  • K KejPi

    If I move Colors.qml to root folder and change CMakeList.txt accordingly:

    set_source_files_properties(Colors.qml PROPERTIES QT_QML_SINGLETON_TYPE TRUE)
qt_add_qml_module(appSingletonTest
    URI SingletonTest
    VERSION 1.0
    QML_FILES qml/main.qml
              Colors.qml
)

    I get this error when I run the application:

    qrc:/SingletonTest/qml/main.qml:14: ReferenceError: Colors is not defined
    K Offline
    K Offline
    KejPi
    wrote on last edited by KejPi
    #7

    It seems all QML files must be in root folder including some other custom components files.

    If I do this, it works:

    set_source_files_properties(Colors.qml PROPERTIES QT_QML_SINGLETON_TYPE TRUE)
qt_add_qml_module(appSingletonTest
    URI SingletonTest
    VERSION 1.0
    QML_FILES main.qml
              Colors.qml
              SomeComponent.qml
)

    This strange, so far I put all my QML files to dedicated folder (qml/) to separate it from C++ and everything was working (see my first example code) - only the singleton causes some problem.

    I could consider this as workaround but I do not like it since I will mix QML with C++ and it will be a mess :-(

    EDIT: It seems that this construction works too:

    set_source_files_properties(qmlfiles/Colors.qml PROPERTIES QT_QML_SINGLETON_TYPE TRUE)
set_source_files_properties(qmlfiles/main.qml PROPERTIES QT_RESOURCE_ALIAS main.qml)
set_source_files_properties(qmlfiles/Colors.qml PROPERTIES QT_RESOURCE_ALIAS Colors.qml)
set_source_files_properties(qmlfiles/SomeComponent.qml PROPERTIES QT_RESOURCE_ALIAS SomeComponent.qml)
qt_add_qml_module(appSingletonTest
    URI SingletonTest
    VERSION 1.0
    QML_FILES qmlfiles/main.qml
              qmlfiles/Colors.qml
              qmlfiles/SomeComponent.qml
)
    ekkescornerE J 2 Replies Last reply
    0
    • K KejPi

      It seems all QML files must be in root folder including some other custom components files.

      If I do this, it works:

      set_source_files_properties(Colors.qml PROPERTIES QT_QML_SINGLETON_TYPE TRUE)
qt_add_qml_module(appSingletonTest
    URI SingletonTest
    VERSION 1.0
    QML_FILES main.qml
              Colors.qml
              SomeComponent.qml
)

      This strange, so far I put all my QML files to dedicated folder (qml/) to separate it from C++ and everything was working (see my first example code) - only the singleton causes some problem.

      I could consider this as workaround but I do not like it since I will mix QML with C++ and it will be a mess :-(

      EDIT: It seems that this construction works too:

      set_source_files_properties(qmlfiles/Colors.qml PROPERTIES QT_QML_SINGLETON_TYPE TRUE)
set_source_files_properties(qmlfiles/main.qml PROPERTIES QT_RESOURCE_ALIAS main.qml)
set_source_files_properties(qmlfiles/Colors.qml PROPERTIES QT_RESOURCE_ALIAS Colors.qml)
set_source_files_properties(qmlfiles/SomeComponent.qml PROPERTIES QT_RESOURCE_ALIAS SomeComponent.qml)
qt_add_qml_module(appSingletonTest
    URI SingletonTest
    VERSION 1.0
    QML_FILES qmlfiles/main.qml
              qmlfiles/Colors.qml
              qmlfiles/SomeComponent.qml
)
      ekkescornerE Offline
      ekkescornerE Offline
      ekkescorner
      Qt Champions 2016
      wrote on last edited by
      #8

      @KejPi open a bugreport because QML SINGLETON doesn't work if not in root folder

      ekke ... Qt Champion 2016 | 2024 ... mobile business apps

      MesrineM 1 Reply Last reply
      0
      • ekkescornerE ekkescorner

        @KejPi open a bugreport because QML SINGLETON doesn't work if not in root folder

        MesrineM Offline
        MesrineM Offline
        Mesrine
        wrote on last edited by
        #9

        @ekkescorner

        I do not know why the one from the post does not work, but singletons from subdirectories work.

        I used here

        ekkescornerE K 2 Replies Last reply
        0
        • MesrineM Mesrine

          @ekkescorner

          I do not know why the one from the post does not work, but singletons from subdirectories work.

          I used here

          ekkescornerE Offline
          ekkescornerE Offline
          ekkescorner
          Qt Champions 2016
          wrote on last edited by
          #10

          @Mesrine aaah - good to know. just porting my apps from QMake to CMake. next step will be to modernize my apps, where I'll need QML SINGLETONS, too

          ekke ... Qt Champion 2016 | 2024 ... mobile business apps

          1 Reply Last reply
          0
          • K KejPi

            It seems all QML files must be in root folder including some other custom components files.

            If I do this, it works:

            set_source_files_properties(Colors.qml PROPERTIES QT_QML_SINGLETON_TYPE TRUE)
qt_add_qml_module(appSingletonTest
    URI SingletonTest
    VERSION 1.0
    QML_FILES main.qml
              Colors.qml
              SomeComponent.qml
)

            This strange, so far I put all my QML files to dedicated folder (qml/) to separate it from C++ and everything was working (see my first example code) - only the singleton causes some problem.

            I could consider this as workaround but I do not like it since I will mix QML with C++ and it will be a mess :-(

            EDIT: It seems that this construction works too:

            set_source_files_properties(qmlfiles/Colors.qml PROPERTIES QT_QML_SINGLETON_TYPE TRUE)
set_source_files_properties(qmlfiles/main.qml PROPERTIES QT_RESOURCE_ALIAS main.qml)
set_source_files_properties(qmlfiles/Colors.qml PROPERTIES QT_RESOURCE_ALIAS Colors.qml)
set_source_files_properties(qmlfiles/SomeComponent.qml PROPERTIES QT_RESOURCE_ALIAS SomeComponent.qml)
qt_add_qml_module(appSingletonTest
    URI SingletonTest
    VERSION 1.0
    QML_FILES qmlfiles/main.qml
              qmlfiles/Colors.qml
              qmlfiles/SomeComponent.qml
)
            J Offline
            J Offline
            Janson
            wrote on last edited by Janson
            #11
            This post is deleted!
            1 Reply Last reply
            0
            • K Offline
              K Offline
              KejPi
              wrote on last edited by
              #12

              I have a small example project that clearly shows it does not work as expected. I can share it but I do not know how to do it here. Maybe I did something wrong - I have juste created project in QtCreator and moved all QML files in subdirectory.

              1 Reply Last reply
              0
              • MesrineM Mesrine

                @ekkescorner

                I do not know why the one from the post does not work, but singletons from subdirectories work.

                I used here

                K Offline
                K Offline
                KejPi
                wrote on last edited by
                #13

                @Mesrine Could it be that you only have singleton in the module while I have all my QML files there?

                1 Reply Last reply
                0
                • K KejPi

                  I do not know how to attach file, so this is cope and paste of minimal example:

                  CMakeList.txt

                  cmake_minimum_required(VERSION 3.16)

project(SingletonTest VERSION 0.1 LANGUAGES CXX)

set(CMAKE_CXX_STANDARD_REQUIRED ON)

find_package(Qt6 6.4 REQUIRED COMPONENTS Quick)

qt_standard_project_setup()

qt_add_executable(appSingletonTest
    main.cpp
)

set_source_files_properties(qml/Colors.qml PROPERTIES QT_QML_SINGLETON_TYPE TRUE)
qt_add_qml_module(appSingletonTest
    URI SingletonTest
    VERSION 1.0
    QML_FILES qml/main.qml
    QML_FILES qml/Colors.qml
)

# Qt for iOS sets MACOSX_BUNDLE_GUI_IDENTIFIER automatically since Qt 6.1.
# If you are developing for iOS or macOS you should consider setting an
# explicit, fixed bundle identifier manually though.
set_target_properties(appSingletonTest PROPERTIES
#    MACOSX_BUNDLE_GUI_IDENTIFIER com.example.appSingletonTest
    MACOSX_BUNDLE_BUNDLE_VERSION ${PROJECT_VERSION}
    MACOSX_BUNDLE_SHORT_VERSION_STRING ${PROJECT_VERSION_MAJOR}.${PROJECT_VERSION_MINOR}
    MACOSX_BUNDLE TRUE
    WIN32_EXECUTABLE TRUE
)

target_link_libraries(appSingletonTest
    PRIVATE Qt6::Quick
)

include(GNUInstallDirs)
install(TARGETS appSingletonTest
    BUNDLE DESTINATION .
    LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}
    RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR}
)

                  main.cpp:

                  #include <QGuiApplication>
#include <QQmlApplicationEngine>

int main(int argc, char *argv[])
{
    QGuiApplication app(argc, argv);

    QQmlApplicationEngine engine;
    const QUrl url(u"qrc:/SingletonTest/qml/main.qml"_qs);
    QObject::connect(
        &engine,
        &QQmlApplicationEngine::objectCreationFailed,
        &app,
        []() { QCoreApplication::exit(-1); },
        Qt::QueuedConnection);
    engine.load(url);

    return app.exec();
}

                  qml/main.qml:

                  import QtQuick
import SingletonTest

Window {
    width: 640
    height: 480
    visible: true
    title: qsTr("Hello World")

    Rectangle {
        width: parent.width/2
        height: parent.height/2
        anchors.centerIn: parent
        color: Colors.myColor
    }
}

                  qml/Colors.qml:

                  pragma Singleton
import QtQuick

QtObject {
    id: colors
    readonly property color myColor: "red"
}

                  When I run it I get this message:

                  qrc:/SingletonTest/qml/main.qml:14: TypeError: Colors was a singleton at compile time, but is not a singleton anymore.
                  MesrineM Offline
                  MesrineM Offline
                  Mesrine
                  wrote on last edited by Mesrine
                  #14

                  @KejPi

                  I have used your minimal example and works ok :) .

                  The only thing I changed was that instead of CMakeList.txt i named CMakeLists.txt.

                  I have tested it with qt(shared libraries) 6.5,6.6,6.7 in Linux.

                  Make sure you are using the correct CMakeLists.txt.
                  And let us know your platform and Qt version.

                  1 Reply Last reply
                  0
                  • K Offline
                    K Offline
                    KejPi
                    wrote on last edited by KejPi
                    #15

                    Yes, it was only typo, I use the CMakeLists.txt created by Qt Creator.
                    I am running it on MacOS 14.2, Qt version 6.5.3

                    MesrineM 1 Reply Last reply
                    0
                    • K KejPi

                      Yes, it was only typo, I use the CMakeLists.txt created by Qt Creator.
                      I am running it on MacOS 14.2, Qt version 6.5.3

                      MesrineM Offline
                      MesrineM Offline
                      Mesrine
                      wrote on last edited by
                      #16

                      @KejPi
                      Do you run the application that is on the build directory or the installed one?

                      Try putting
                      set_source_files_properties(qml/Colors.qml PROPERTIES QT_QML_SINGLETON_TYPE TRUE)

                      before

                      qt_add_executable(appSingletonTest
    main.cpp
)

                      in your minimal example.
                      If that does not work try removing some macos properties in the CMakeLists.txt.
                      If nothing works I would say you can open a bug as suggested by @ekkescorner

                      K 1 Reply Last reply
                      0
                      • MesrineM Mesrine

                        @KejPi
                        Do you run the application that is on the build directory or the installed one?

                        Try putting
                        set_source_files_properties(qml/Colors.qml PROPERTIES QT_QML_SINGLETON_TYPE TRUE)

                        before

                        qt_add_executable(appSingletonTest
    main.cpp
)

                        in your minimal example.
                        If that does not work try removing some macos properties in the CMakeLists.txt.
                        If nothing works I would say you can open a bug as suggested by @ekkescorner

                        K Offline
                        K Offline
                        KejPi
                        wrote on last edited by KejPi
                        #17

                        @Mesrine I run the application directly from Qt Creator after building it.
                        Moving set_source_files_properties did not help, the problem is the same.

                        Bug report created https://bugreports.qt.io/browse/QTBUG-121758

                        1 Reply Last reply
                        0

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