i'm trying to implement a ComboBox in QML and C++, in which i can dynamically change the content of my ComboBox. I'm providing a QStringList as ComboBox-Model and want to insert/remove an entry from the ComboBox with two buttons.
I can display the QStringList in my ComboBox, but when i click on the Add-Button for example, my QStringList gets updated in my class, but somehow the View does not update the ComboBox entrys. What should i do, to tell the View that my ComboBox-Model has updated?
This is my code:
comboboxmodel.h
#ifndef COMBOBOXMODEL_H
#define COMBOBOXMODEL_H
#include <QObject>
#include <QStringList>
class ComboBoxModel : public QObject
{
Q_OBJECT
Q_PROPERTY(QStringList comboList READ comboList WRITE setComboList NOTIFY comboListChanged)
Q_PROPERTY(int count READ count WRITE setCount NOTIFY countChanged)
public:
ComboBoxModel(QObject *parent = 0);
ComboBoxModel(const QStringList &list,int count, QObject *parent = 0);
const QStringList comboList();
void setComboList(const QStringList &comboList);
int count();
void setCount(int cnt);
Q_INVOKABLE void addElement(const QString &element);
Q_INVOKABLE void removeElement(int index);
signals:
void comboListChanged();
void countChanged();
public slots:
private:
QStringList m_comboList;
int m_count;
};
#endif // COMBOBOXMODEL_H
comboboxmodel.cpp
#include "comboboxmodel.h"
#include "qdebug.h"
ComboBoxModel::ComboBoxModel(QObject *parent) :
QObject(parent)
{
}
ComboBoxModel::ComboBoxModel(const QStringList &list, int count, QObject *parent) :
QObject(parent), m_comboList(list), m_count(count)
{
}
const QStringList ComboBoxModel::comboList()
{
return m_comboList;
}
void ComboBoxModel::setComboList(const QStringList &comboList)
{
if (m_comboList != comboList)
{
m_comboList = comboList;
emit comboListChanged();
}
}
int ComboBoxModel::count()
{
return m_count;
}
void ComboBoxModel::setCount(int cnt)
{
if (cnt != m_count)
{
m_count = cnt;
emit countChanged();
}
}
void ComboBoxModel::addElement(const QString &element)
{
m_comboList.append(element);
emit comboListChanged();
setCount(m_comboList.count());
emit countChanged();
for (int i = 0; i<m_count; i++)
{
qDebug() << m_comboList.at(i);
}
}
void ComboBoxModel::removeElement(int index)
{
if (index < m_comboList.count())
{
m_comboList.removeAt(index);
emit comboListChanged();
setCount(m_comboList.count());
emit countChanged();
}
for (int i = 0; i<m_count; i++)
{
qDebug() << m_comboList.at(i);
}
}
main.cpp
#include <QApplication>
#include <QQmlApplicationEngine>
#include <qqmlengine.h>
#include <qqmlcontext.h>
#include <qqml.h>
#include <QStringList>
#include "comboboxmodel.h"
int main(int argc, char *argv[]) {
QApplication app(argc, argv);
QQmlApplicationEngine engine;
ComboBoxModel combo;
QStringList tmp;
tmp << "1" << "2" << "3" << "4" << "5" << "6" << "7";
combo.setComboList(tmp);
QQmlContext *ownContext = engine.rootContext();
ownContext->setContextProperty("myModel", QVariant::fromValue(combo.comboList()));
QQmlContext *classContext = engine.rootContext();
classContext->setContextProperty("comboModel", &combo);
engine.load(QUrl(QStringLiteral("qrc:/main.qml")));
return app.exec(); }
main.qml
import QtQuick 2.3 import QtQuick.Controls 1.2
ApplicationWindow {
visible: true
width: 640
height: 480
title: qsTr("Hello World")
menuBar: MenuBar {
Menu {
title: qsTr("File")
MenuItem {
text: qsTr("&Open")
onTriggered: console.log("Open action triggered");
}
MenuItem {
text: qsTr("Exit")
onTriggered: Qt.quit();
}
}
}
Text {
text: qsTr("Hello World")
anchors.centerIn: parent
}
ComboBox {
id: comboBox1
x: 258
y: 54
model: myModel
editable: true
onAccepted: {
if (editableCombo.find(currentText) === -1) {
model.append({text: editText})
currentIndex = editableCombo.find(editText)
}
}
}
Button {
id: button1
x: 280
y: 139
text: qsTr("Remove Item")
onClicked: comboModel.removeElement(comboBox1.currentIndex)
}
Rectangle{
x: 281
y: 316
width: 80
height: 20
color: "white"
TextEdit {
id: textEdit1
width: 80
height: 20
text: qsTr("Text Edit")
font.pixelSize: 12
}
}
Button {
id: button2
x: 280
y: 388
text: qsTr("Add Item")
onClicked: comboModel.addElement(textEdit1.text)
} }
So i finnaly figured out how to do this kind of stuff.
In main.qml it should be:
model: comboModel.comboList
instead of:
model: myModel
Now i can add/remove items from my list and they are displayed correctly.
Thanks for your hint BaCaRoZzo.
Can somebody change this subject to "Solved"?
The example has helped me a lot, thank you! Here's a slightly modified version as a finished working example:
comboboxmodel.h
#ifndef COMBOBOXMODEL_H
#define COMBOBOXMODEL_H
#include <QObject>
#include <QStringList>
class ComboBoxModel : public QObject
{
Q_OBJECT
Q_PROPERTY(QStringList comboList READ comboList WRITE setComboList NOTIFY comboListChanged)
Q_PROPERTY(int count READ count WRITE setCount NOTIFY countChanged)
Q_PROPERTY(int currentIndex READ currentIndex WRITE setcurrentIndex NOTIFY currentIndexChanged)
public:
ComboBoxModel(QObject *parent = 0);
ComboBoxModel(const QStringList &list,int count, QObject *parent = 0);
const QStringList comboList();
void setComboList(const QStringList &comboList);
int count();
void setCount(int cnt);
int currentIndex();
void setcurrentIndex(int index);
Q_INVOKABLE void addElement(const QString &element);
Q_INVOKABLE void removeElement(int index);
signals:
void comboListChanged();
void countChanged();
void currentIndexChanged();
public slots:
private:
QStringList m_comboList;
int m_count;
int m_currentIndex;
};
#endif // COMBOBOXMODEL_H
comboboxmodel.cpp
#include "comboboxmodel.h"
#include "qdebug.h"
ComboBoxModel::ComboBoxModel(QObject *parent) :
QObject(parent)
{
}
ComboBoxModel::ComboBoxModel(const QStringList &list, int count, QObject *parent) :
QObject(parent), m_comboList(list), m_count(count)
{
}
const QStringList ComboBoxModel::comboList()
{
return m_comboList;
}
void ComboBoxModel::setComboList(const QStringList &comboList)
{
if (m_comboList != comboList)
{
m_comboList = comboList;
emit comboListChanged();
}
}
int ComboBoxModel::count()
{
return m_count;
}
void ComboBoxModel::setCount(int cnt)
{
if (cnt != m_count)
{
m_count = cnt;
emit countChanged();
}
}
int ComboBoxModel::currentIndex()
{
return m_currentIndex;
}
void ComboBoxModel::setcurrentIndex(int index)
{
if (index != m_currentIndex)
{
m_currentIndex = index;
qDebug()<<"current index is"<<index;
emit currentIndexChanged();
}
}
void ComboBoxModel::addElement(const QString &element)
{
m_comboList.append(element);
emit comboListChanged();
setCount(m_comboList.count());
emit countChanged();
for (int i = 0; i<m_count; i++)
{
qDebug() << m_comboList.at(i);
}
}
void ComboBoxModel::removeElement(int index)
{
if (index < m_comboList.count())
{
m_comboList.removeAt(index);
emit comboListChanged();
setCount(m_comboList.count());
emit countChanged();
}
for (int i = 0; i<m_count; i++)
{
qDebug() << m_comboList.at(i);
}
}
main.cpp
#include <QGuiApplication>
#include <QQmlApplicationEngine>
#include <QQmlContext>
#include <QStringList>
#include "comboboxmodel.h"
int main(int argc, char *argv[])
{
QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);
QGuiApplication app(argc, argv);
QQmlApplicationEngine engine;
ComboBoxModel combo;
QStringList tmp;
tmp << "1" << "2" << "3" << "4" << "5" << "6" << "7";
combo.setComboList(tmp);
QQmlContext *ownContext = engine.rootContext();
ownContext->setContextProperty("myModel", QVariant::fromValue(combo.comboList()));
QQmlContext *classContext = engine.rootContext();
classContext->setContextProperty("comboModel", &combo);
engine.load(QUrl(QStringLiteral("qrc:/main.qml")));
if (engine.rootObjects().isEmpty())
return -1;
return app.exec();
}
main.qml
import QtQuick 2.3
import QtQuick.Controls 2.2
ApplicationWindow {
visible: true
width: 640
height: 480
title: qsTr("Hello World")
Text {
text: qsTr("Hello World")
anchors.centerIn: parent
}
ComboBox {
id: comboBox1
x: 258
y: 54
model: comboModel.comboList
onActivated: {
console.log("combomodel activated" + comboBox1.currentIndex)
comboModel.currentIndex = comboBox1.currentIndex
}
}
Button {
id: button1
x: 280
y: 139
text: qsTr("Remove Item")
onClicked: comboModel.removeElement(comboBox1.currentIndex)
}
Rectangle{
x: 281
y: 316
width: 80
height: 20
color: "white"
TextEdit {
id: textEdit1
width: 80
height: 20
text: qsTr("Text Edit")
font.pixelSize: 12
}
}
Button {
id: button2
x: 280
y: 388
text: qsTr("Add Item")
onClicked: comboModel.addElement(textEdit1.text)
} }
pro-file
QT += quick
CONFIG += c++11
DEFINES += QT_DEPRECATED_WARNINGS
SOURCES += main.cpp \
comboboxmodel.cpp
RESOURCES += qml.qrc
QML_IMPORT_PATH =
QML_DESIGNER_IMPORT_PATH =
qnx: target.path = /tmp/$${TARGET}/bin
else: unix:!android: target.path = /opt/$${TARGET}/bin
!isEmpty(target.path): INSTALLS += target
HEADERS += \
comboboxmodel.h
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