Error: Qt.createQmlObject(): Component is not ready

Question

我想使用 Qt.createQmlObject() 函数从 QML 字符串创建一个 QML 项目，就像在 example 中一样，但第一次得到错误："Error: Qt.createQmlObject(): Component is not ready"，在第二次项目中正确创建，有什么问题吗？

你可以看到 - 我正在尝试各种项目：Item、Rectangle、Component（只有一个有 "status" 属性）

测试应用程序是： main.cpp:

  #include <QApplication>
  #include <QWSServer>
  #include <QDeclarativeView>

  int main(int argc, char *argv[])
  {
    QApplication a(argc, argv, QApplication::GuiServer);

    QDeclarativeView view;
    view.setMinimumSize(100,100);
    view.setResizeMode(QDeclarativeView::SizeRootObjectToView);
    view.show();
    view.setSource(QUrl::fromUserInput("qrc:/createFromStringTest.qml"));

    return a.exec();
  }

createFromStringTest.qml:

        import QtQuick 1.1

        Rectangle {
            id: rootRectangle
            objectName: "rootRectangle"
            anchors.centerIn: parent
            anchors.fill: parent
            color: "gray"
            border.width: 5
            border.color: "black"
            width: 50
            height: 50

            property int testCount: 0

            MouseArea {
                anchors.fill: parent
                onClicked: {
                    testCount +=1;
                    console.log("====================== Runing test "+testCount+" ======================");
                    tests()
                }
            }

            // what is right?
            Item{
                id: parentItem
                objectName: "parentItem"
                Component.onCompleted: {
                    console.log("parentItem loaded");
                }
            }

            Component {
                id: parentComponent
                Item {
                    id: parentComponentItem
                    Component.onCompleted: {
                        console.log("parentComponentItem loaded");
                    }
                }
            }

            property list<Item> parentListItem
            property list<Component> parentListComponent

            Rectangle {
                id: parentRectangle
                objectName: "parentRectangle"
                Component.onCompleted: {
                    console.log("parentRectangle loaded");
                }
            }

            Component.onCompleted: {
                console.log("rootRectangle loaded ");
            }

            Component.onDestruction: {
                console.log("rootRectangle destroyed ");
            }

            function tests(){
                try{
                    var newObjectparentItem = Qt.createQmlObject('import QtQuick 1.1; Rectangle {objectName: "dynparentItem";anchors.centerIn: parent; anchors.fill: parent; border.width: 10; border.color: "red";}',parentItem,"parentItem:");
                    console.log("parentItem OK ");
                }catch(e){
                    console.log("parentItem error: "+e);
                }

                try{
                    var newObjectparentComponent = Qt.createQmlObject('import QtQuick 1.1; Rectangle {objectName: "dynparentComponent";anchors.centerIn: parent; anchors.fill: parent; border.width: 10; border.color: "red";}',parentComponent,"parentComponent:");
                    console.log("parentComponent OK ");
                }catch(e){
                    console.log("parentComponent error: "+e);
                }

                try{
                    var newObjectparentComponentItem = Qt.createQmlObject('import QtQuick 1.1; Rectangle {objectName: "dynparentComponentItem";anchors.centerIn: parent; anchors.fill: parent; border.width: 10; border.color: "red";}',parentComponentItem,"parentComponentItem:");
                    console.log("parentComponentItem OK ");
                }catch(e){
                    console.log("parentComponentItem error: "+e);
                }

                try{
                    var newObjectparentListItem = Qt.createQmlObject('import QtQuick 1.1; Rectangle {objectName: "dynparentListItem";anchors.centerIn: parent; anchors.fill: parent; border.width: 10; border.color: "red";}',parentListItem,"parentListItem:");
                    console.log("parentListItem OK ");
                }catch(e){
                    console.log("parentListItem error: "+e);
                }

                try{
                    var newObjectparentListComponent = Qt.createQmlObject('import QtQuick 1.1; Rectangle {objectName: "dynparentListComponent";anchors.centerIn: parent; anchors.fill: parent; border.width: 10; border.color: "red";}',parentListComponent,"parentListComponent:");
                    console.log("parentListComponent OK ");
                }catch(e){
                    console.log("parentListComponent error: "+e);
                }

                try{
                    var newObjectparentRectangle = Qt.createQmlObject('import QtQuick 1.1; Rectangle {objectName: "dynparentRectangle";anchors.centerIn: parent; anchors.fill: parent; border.width: 10; border.color: "red";}',parentRectangle,"parentRectangle:");
                    console.log("parentRectangle OK ");
                }catch(e){
                    console.log("parentRectangle error: "+e);
                }
            }
        }

输出：

Qml debugging is enabled. Only use this in a safe environment!
rootRectangle loaded 
parentRectangle loaded
parentItem loaded
====================== Runing test 1 ======================
parentItem error: Error: Qt.createQmlObject(): Component is not ready
parentComponent error: Error: Qt.createQmlObject(): Component is not ready
parentComponentItem error: ReferenceError: Can't find variable: parentComponentItem
parentListItem error: Error: Qt.createQmlObject(): Missing parent object
parentListComponent error: Error: Qt.createQmlObject(): Missing parent object
parentRectangle error: Error: Qt.createQmlObject(): Component is not ready
====================== Runing test 2 ======================
parentItem OK 
parentComponent OK 
parentComponentItem error: ReferenceError: Can't find variable: parentComponentItem
parentListItem error: Error: Qt.createQmlObject(): Missing parent object
parentListComponent error: Error: Qt.createQmlObject(): Missing parent object
parentRectangle OK 
rootRectangle destroyed

使用 Qt 4.8

Answer 1

对于像您这样的情况，请立即在此 QML 文件中使用 Qt.createComponent to dynamically initialize the component you use. With component initialized you can call then Component.CreateObject. Or you could have used one parentComponent for that: parentComponent.CreateObject(QmlItem, "QML properties"). I usually use Qt.createQmlObject 使用 QML window 执行动态操作，不要为其创建任何新的 QML 上下文。

请注意，在大多数情况下，您甚至不需要使用上述任何一种方法，只需操作一些 QML Repeater 及其数据模型即可。这样您就可以提供智能委托来自定义动态创建的项目。但是这个话题不仅仅是对你问题的回答。

Answer 2

函数的第三个参数出错 Qt.createQmlObject（QML 字符串，父 ID，文件名）我的示例中的文件名包含“：”符号 - 没有它按预期工作！

Answer 3

根据我的经验，我在使用 Qt.createComponent + Component.createObject 动态创建对象时遇到 "Component is not ready" 错误，并且组件中存在 QML 错误。

发现错误的一种方法是将该组件的实例静态添加到您的 QML 应用程序，以便在运行应用程序时打印带有行号的错误。

Error: Qt.createQmlObject(): Component is not ready

Error: Qt.createQmlObject(): Component is not ready

qt

components

dynamic

qml

qt-quick