QList<int>不能用作中继器的模型

2022-01-19 00:00:00 qt qml javascript c++

我有一个 QObject 属性声明为:

I have a QObject property declared as:

Q_PROPERTY( QList< int > keys READ getKeys NOTIFY keysChanged )

在 docs 声明如下:

某些 C++ 序列类型在 QML 中被透明地支持为JavaScript 数组类型.

Certain C++ sequence types are supported transparently in QML as JavaScript Array types.

具体来说，QML 目前支持:

In particular, QML currently supports:

  • QList<诠释 >

...

但是，当我使用此属性来驱动 Repeater 模型时:

However, when I use this property to drive a Repeater model:

QtObject {
    id: d_
    property var keys: base.proxy.keys // A binding to the C++ keys property
    onKeysChanged: {
        ...
    }
}

Column {
    spacing: 4

    Repeater {
        id: repeater
        model: d_.keys
        delegate: Rectangle {
            height: 24
            width: 24
            color: "red"
        }
    }
}

Repeater 模型不产生委托.如果我查询 d_.keys 的长度，它会显示正确的数量，如果我从 C++ 更改属性，则会触发 d_.onKeyChanged:{} - 但Repeater 从不构建任何东西.

The Repeater model produces no delegates. If I query the length of d_.keys, it shows the correct quantity, and if I change the property from C++, d_.onKeyChanged:{} is triggered ― but the Repeater never builds anything.

如果我将 QML keys 属性更改为 JS 数组:

If I change the QML keys property to be a JS array:

property var keys: [1,2,3]

Repeater 按预期工作.如果我使用 C++ 属性，但手动将数据转换为 JS 数组，它也可以按预期工作:

The Repeater works as expected. If I use the C++ property, but manually convert the data to a JS array, it also works as expected:

QtObject {
    id: d_
    property var keys: base.proxy.keys

    onKeysChanged: {
        var list = [];
        for ( var i = 0; i < keys.length; ++i ) {
            list.push( keys[i] );
        }
        repeater.model = list;
    }
}

这强烈表明，不管文档怎么说，QList<int> 不 等同于 JS 数组.是我做错了什么，还是这是一个错误?

This strongly indicates that despite what the docs say, QList<int> is not equivalent to a JS array. Am I doing something wrong, or is this a bug?

推荐答案

如上所述 here，QVariantList被转换为JS数组，因此问题可能出在内容的类型上不是列表本身.

As described here, the QVariantList is converted to a JS array, therefore the problem may be the type of the content not the list itself.

也就是说，我同意你的观点，即文档不够清晰，因为 QList 似乎也是一个有效的替代方案.

That said, I agree with you that the documentation is not clear enough since the QList seems to be a valid alternative as well.

相关文章