How to convert enum to QString?

Question

I am trying to use the Qt reflection for converting enum to QString.

Here is the part of code:

class ModelApple
{
    Q_GADGET
    Q_ENUMS(AppleType)         


        

Answer 1

Much more elegant way found (Qt 5.9), just one single line, with the help of mighty QVariant.

turns enum into string:

QString theBig = QVariant::fromValue(ModelApple::Big).toString();

Perhaps you don't need QMetaEnum anymore.

Sample code here:

ModelApple (no need to claim Q_DECLARE_METATYE)

class ModelApple : public QObject
{
    Q_OBJECT
public:
    enum AppleType {
      Big,
      Small
    };
    Q_ENUM(AppleType)
    explicit ModelApple(QObject *parent = nullptr);
};

And I create a widget application, calling QVaraint function there :

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <modelapple.h>
#include <QDebug>

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);

    QString s = QVariant::fromValue(ModelApple::Big).toString();
    qDebug() << s;

}

MainWindow::~MainWindow()
{
    delete ui;
}

You can see that i try to output the string on console , which really did:

And sorry for reverse casting , i tried successfully in some project , but some how this time i met compiling error. So i decide to remove it from my answer.

Answer 2

The following should get you going:

QString convertEnumToQString(ModelApple::AppleType type) {
    const QMetaObject metaObject = ModelApple::staticMetaObject;
    int enumIndex = metaObject.indexOfEnumerator("AppleType");
    if(enumIndex == -1) {
        /* The enum does not contain the specified enum */
        return "";
    }
    QMetaEnum en = metaObject.enumerator(enumIndex);
    return QString(en.valueToKey(type));
}

Answer 3

How about:

QString convertEnumToQString(ModelApple::AppleType type)
{
    const QMetaObject &mo = ModelApple::staticMetaObject;
    int index = mo.indexOfEnumerator("AppleType");
    QMetaEnum metaEnum = mo.enumerator(index);
    return metaEnum.valueToKey(type);
}

UPDATED: For Qt 5.5, see this answer

Answer 4

You need to use Q_ENUM macro, which registers an enum type with the meta-object system.

enum AppleType {
  Big,
  Small
};
Q_ENUM(AppleType)

And now you can use the QMetaEnum class to access meta-data about an enumerator.

QMetaEnum metaEnum = QMetaEnum::fromType<ModelApple::AppleType>();
qDebug() << metaEnum.valueToKey(ModelApple::Big);

---

Here is a generic template for such utility:

template<typename QEnum>
std::string QtEnumToString (const QEnum value)
{
  return std::string(QMetaEnum::fromType<QEnum>().valueToKey(value));
}

Answer 5

For the global Enum declaring use this in any header file:

namespace YourNamespace {

Q_NAMESPACE

enum YourEnum: int {

    EnumValue1,
    EnumValue2
};
Q_ENUM_NS(YourEnum)

}

and this where you want to get Enum description:

QMetaEnum metaEnum = QMetaEnum::fromType<YourEnum>();
qDebug() << "Enum description: " << metaEnum.name() << "::" << metaEnum.valueToKey(YourEnum::EnumValue2);

Answer 6

I faced the same problem and this is how i solved it. This is especially for Qt 4.8

QString string = enumToString(ModelApple::Big);

QString ModelApple::enumToString(AppleType apple)
{
    int index = metaObject()->indexOfEnumerator("AppleType");
    QMetaEnum metaEnum = metaObject()->enumerator(index);
    return metaEnum.valueToKey(apple);
}