QQmlPropertyMap how to notify QML of updates
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@SPlatten https://doc.qt.io/qt-5.15/qqmlpropertymap.html
connect the signal
void valueChanged(const QString &key, const QVariant &value)
in your qml and then check if the key is equal to your variable name. If yes, you know it is changed. No timestamp is needed. -
@SPlatten https://doc.qt.io/qt-5.15/qqmlpropertymap.html
connect the signal
void valueChanged(const QString &key, const QVariant &value)
in your qml and then check if the key is equal to your variable name. If yes, you know it is changed. No timestamp is needed. -
@JoeCFD , the timestamp is needed so I can work out how old since the last update, if the time elapsed is greater than a specified period then the data is stale.
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@JoeCFD The documentation for valueChanged says: Note: valueChanged() is NOT emitted when changes are made by calling insert() or clear() - it is only emitted when a value is updated from QML.
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@SPlatten Do not calling insert() mean binding or clear() mean release binding? It makes sense that the value is not changed.
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@SPlatten Read the example:
https://doc.qt.io/qt-5.15/qqmlpropertymap.htmlQQmlPropertyMap ownerData; ownerData.insert("name", QVariant(QString("John Smith"))); ==> will not trigger valueChanged, sort of like initialization ownerData.insert("phone", QVariant(QString("555-5555")));write a small program to test it.
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@SPlatten Read the example:
https://doc.qt.io/qt-5.15/qqmlpropertymap.htmlQQmlPropertyMap ownerData; ownerData.insert("name", QVariant(QString("John Smith"))); ==> will not trigger valueChanged, sort of like initialization ownerData.insert("phone", QVariant(QString("555-5555")));write a small program to test it.
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@JoeCFD , is it only the initial insert of an item that does not trigger the valueChanged signal ?
I will try this out tomorrow, thank you.
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@SPlatten I haven't followed this whole thread so apologies if I have missed something, but but regarding your most recent question, could you set your
QQmlPropertyMapas a context property in your C++ back end? You would then be able in QML to use the name that you registered the context property as. -
Might be able to try:
Item{
Property var myData: backendQqmlPropertyMap.name
OnMyDataChanged{
// Doathing
}
}Sorry for formatting, on a phone currently!
