How to use C struct array for QML ComboBox?-CodePudding

I've got a struct with two fields, for example:

struct testStruct
{
  Q_GADGET
  Q_PROPERTY(QString text MEMBER m_text);
  Q_PROPERTY(QString value MEMBER m_value);

public:
  QString m_text;
  QString m_value;
};

There is a QList<testStruct> m_testStructs member of my "AppEngine" class exposed to QML via Q_PROPERTY(QList<testStruct> testStructs READ testStructs NOTIFY testStructsChanged).
It is filled like that:

testStruct newStruct1, newStruct2;
  newStruct1.m_text = "text1";
  newStruct1.m_value = "value1";
  newStruct2.m_text = "text2";
  newStruct2.m_value = "value2";
  m_testStructs << newStruct1 << newStruct2;

So I want to see "text" members in ComboBox list and use "value" members in further operations.

In fact QML ComboBox popup shows me the list of objects names when I set ComboBox's "textRole" property to "text" and "valueRole" to "value", but it does nothing for "currentText" or "currentValue" properties when I click the item, only "currentIndex" changes. Also "displayText" remains blank.

This is what I get in console when clicking those items:

qml: currentIndex: 0; currentText:  ; currentValue: undefined
qml: currentIndex: 1; currentText:  ; currentValue: undefined

So I see that ComboBox gets members of struct, but doesn't want to work with them. What should I do to make "currentText" and "currentValue" members of ComboBox work as they should?

Here are all the needed files:

main.cpp

#include <QGuiApplication>
#include <QQmlApplicationEngine>
#include <QQmlContext>
#include "appengine.h"

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

  QQmlApplicationEngine engine;
  const QUrl url(u"qrc:/qml_testComboBoxStruct/main.qml"_qs);
  QObject::connect(&engine, &QQmlApplicationEngine::objectCreated,
                   &app, [url](QObject *obj, const QUrl &objUrl) {
    if (!obj && url == objUrl)
      QCoreApplication::exit(-1);
  }, Qt::QueuedConnection);

  //exposing AppEngine class to QML
  AppEngine appEngineObj;
  QQmlContext *context = engine.rootContext();
  context->setContextProperty("AppEngine", &appEngineObj);

  engine.load(url);
  return app.exec();
}

my custom class header AppEngine.h

#ifndef APPENGINE_H
#define APPENGINE_H

#include <QObject>
#include <QDebug>

struct testStruct
{
  Q_GADGET
  Q_PROPERTY(QString text MEMBER m_text);
  Q_PROPERTY(QString value MEMBER m_value);

public:
  QString m_text;
  QString m_value;
};
Q_DECLARE_METATYPE(testStruct)

class AppEngine : public QObject
{
  Q_OBJECT
  Q_PROPERTY(QList<testStruct> testStructs READ testStructs NOTIFY testStructsChanged);

public:
  explicit AppEngine(QObject *parent = nullptr);
  QList<testStruct> testStructs();

private:
  QList<testStruct> m_testStructs;

signals:
  void testStructsChanged();
};

#endif // APPENGINE_H

my custom class cpp file AppEngine.cpp

#include "appengine.h"

AppEngine::AppEngine(QObject *parent)
  : QObject{parent}
{
  testStruct newStruct1, newStruct2;
  newStruct1.m_text = "text1";
  newStruct1.m_value = "value1";
  newStruct2.m_text = "text2";
  newStruct2.m_value = "value2";
  m_testStructs << newStruct1 << newStruct2;
  qDebug() << "m_testStructs.length():" << m_testStructs.length();
}

QList<testStruct> AppEngine::testStructs()
{
  qDebug() << "testStructs()";
  return m_testStructs;
}

main.qml

import QtQuick
import QtQuick.Controls

Window {
  width: 640
  height: 480
  visible: true
  title: qsTr("C   struct to QML ComboBox")

  ComboBox
  {
    anchors.centerIn: parent
    width: 180
    height: 30
    id: comboBoxID
    textRole: "text"
    valueRole: "value"
    model: AppEngine.testStructs

    onActivated:
    {
      console.log('currentIndex:', currentIndex, '; currentText:', currentText, ';currentValue:', currentValue);
    }
  }
}

CodePudding user response：

As I checked in the main.qml model property cant find and understand as you show it is undefined.

qml: currentIndex: 0; currentText:  ; currentValue: undefined
qml: currentIndex: 1; currentText:  ; currentValue: undefined

from