How to Pass Non-Primitive Types Between C Signals and QML Slots?

Troubleshooting Signal-Slot Connection Between C and QML

In Qt, connecting signals from C classes to QML slots can sometimes encounter errors when dealing with non-primitive types. For instance, attempting to pass a QString from a C signal to a QML slot may result in the error: "Object::connect: No such slot QDeclarativeRectangle_QML_2::updateViewWithItem(QString)".

Solution: Using Connections

To resolve this issue, utilize QML connections instead of the traditional QObject::connect method. Here's how to implement it:

1. Add the object to QML: In your C code, expose the myObj object to QML using setContextProperty.

   <code class="cpp">qmlVectorForm->rootContext()->setContextProperty("YourObject", myOb);</code>

2. Define the signal: In your C class, declare the signal as follows:

   <code class="cpp">finishedGatheringDataForItem(QString signalString)</code>

3. Add Connections in QML: In your QML file, define the connections like this:

   <code class="qml">Connections {
       target: YourObject
       onFinishedGatheringDataForItem: {
           qmlString = signalString
       }
   }</code>

By following these steps, you can establish a connection between the C signal and the QML slot, allowing you to pass and handle custom data types seamlessly.

The above is the detailed content of How to Pass Non-Primitive Types Between C Signals and QML Slots?. For more information, please follow other related articles on the PHP Chinese website!