编写和阅读自定义类到QSettings [英] Writing and reading custom class to QSettings

问题描述

我需要通过QSettings在注册表中存储自定义类的实例。从Qt的文档阅读后，我认为我已经实现了所需的功能，但我不设法保存任何东西。

I need to store instances of a custom class in the registry via QSettings. After reading from Qt's documentation, I think I have implemented the needed functions but I don't manage to save anything.

这是我的自订类别：

class SRSDefinition{
public:
    SRSDefinition(QString name, QString definition) : qsName(name), qsDefinition(definition)
    {
        qRegisterMetaType<SRSDefinition>("SRSDefinition");
        qRegisterMetaTypeStreamOperators<SRSDefinition>("SRSDefinition");       
    }
    SRSDefinition(const SRSDefinition& original) : qsName(original.qsName), qsDefinition(original.qsDefinition) {}
    SRSDefinition() : qsName(""), qsDefinition(""){}
    ~SRSDefinition();
    QString qsName;
    QString qsDefinition;
private:
    friend QDataStream& operator << (QDataStream& out, const SRSDefinition& valeur) {out << valeur.qsName << valeur.qsDefinition; return out; }
    friend QDataStream& operator >> (QDataStream& in, SRSDefinition& valeur) {in >> valeur.qsName >> valeur.qsDefinition; return in;}
};
Q_DECLARE_METATYPE(SRSDefinition)
QDataStream& operator << (QDataStream& out, const SRSDefinition& Valeur);
QDataStream& operator >> (QDataStream& in, SRSDefinition& Valeur);

在注册表中保存：

QSettings settings("Organization", "Application");
QVariant variant;
variant.setValue(QVariant::fromValue<SRSDefinition>(m_srsSelected));
settings.setValue("Shared/RecentSRS", variant);

从注册表载入：

QSettings settings("Organization", "Application");
m_srsSelected = settings.value("Shared/RecentSRS").value<SRSDefinition>();

在注册表中创建一个新的键，但它包含十六进制代码，我认为只是名称的类...

A new key in the registry is created, but it contains hex code that I think is just the name of the class...

任何想法如何有效地存储值？

Any idea how to effectively store the values ?

推荐答案

使用 qRegisterMetaTypeStreamOperators< YourType& （YourType），以使用QVariant启用自定义类型的序列化/反序列化。该函数在Qt的元类型系统中注册你的类型的QDataStream输入/输出函数，以便在保存/加载包含你的自定义类型的变量时调用它们。

Use qRegisterMetaTypeStreamOperators<YourType>("YourType") to enable serialization/de-serialization of custom types with QVariant. This function registers your type's QDataStream input/output functions with Qt's metatype system so that it can invoke them when saving/loading a variant containing your custom type.

#include <QtCore/QDebug>
#include <QtCore/QDataStream>
#include <QtCore/QSettings>

struct CustomType {
    QString name;
    int age;
};

Q_DECLARE_METATYPE(CustomType);

QDataStream& operator<<(QDataStream& out, const CustomType& v) {
    out << v.name << v.age;
    return out;
}

QDataStream& operator>>(QDataStream& in, CustomType& v) {
    in >> v.name;
    in >> v.age;
    return in;
}

int main(int,char**) {

    qRegisterMetaTypeStreamOperators<CustomType>("CustomType");

    {
        CustomType t;
        t.name = "John Smith";
        t.age = 42;
        QSettings s("config.ini", QSettings::IniFormat);
        s.setValue("user", QVariant::fromValue(t));
    }

    {
        QSettings s("config.ini", QSettings::IniFormat);
        QVariant value = s.value("user");
        CustomType t = value.value<CustomType>();

        qDebug() << t.name << t.age;
    }


    return 0;
}

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