Error serializing d-pointer object using QDataStream

[jiveaxe]

Hi, I'm trying to serialize a pimpl object, but get a compilation error. I prepared a minimal example:

record_p.h

#include "record.h"
 
namespace MyApp {
 
class RecordPrivate : public QObject
{
    Q_OBJECT
 
public:
    RecordPrivate ( Record* qq, QObject* parent = 0 );
 
    QString name() const;
    uint age() const;
 
private:
    Record* const q;
 
    QString m_name;
    uint m_age;
};
 
}

#include "record.h"

namespace MyApp {

class RecordPrivate : public QObject
{
    Q_OBJECT

public:
    RecordPrivate ( Record* qq, QObject* parent = 0 );

    QString name() const;
    uint age() const;

private:
    Record* const q;

    QString m_name;
    uint m_age;
};

}

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record.h

namespace MyApp {
 
class RecordPrivate;
 
class Record : public QObject
{
    Q_OBJECT
    Q_PROPERTY( QString name READ name CONSTANT )
    Q_PROPERTY( uint age READ age CONSTANT )
 
public:
    explicit Record(QObject *parent = 0);
    virtual ~Record();
 
    QString name() const;
    uint age() const;
 
private:
    Q_DISABLE_COPY( Record )
    RecordPrivate* const d;
    friend class RecordPrivate;
 
};
 
typedef QSharedPointer<Record> RecordPtr;
 
}
 
QDataStream& operator<<( QDataStream& dataStream, const MyApp::RecordPtr record );
 
Q_DECLARE_METATYPE( MyApp::RecordPtr )

namespace MyApp {

class RecordPrivate;

class Record : public QObject
{
    Q_OBJECT
    Q_PROPERTY( QString name READ name CONSTANT )
    Q_PROPERTY( uint age READ age CONSTANT )

public:
    explicit Record(QObject *parent = 0);
    virtual ~Record();

    QString name() const;
    uint age() const;

private:
    Q_DISABLE_COPY( Record )
    RecordPrivate* const d;
    friend class RecordPrivate;

};

typedef QSharedPointer<Record> RecordPtr;

}

QDataStream& operator<<( QDataStream& dataStream, const MyApp::RecordPtr record );

Q_DECLARE_METATYPE( MyApp::RecordPtr )

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record.cpp

#include "record_p.h"
 
using namespace MyApp;
 
RecordPrivate::RecordPrivate ( Record* qq, QObject* parent ) :
    QObject ( parent ),
    q ( qq )
{
}
 
uint RecordPrivate::age() const
{
    return m_age;
}
 
QString RecordPrivate::name() const
{
    return m_name;
}
 
Record::Record(QObject *parent) :
    QObject(parent),
    d ( new RecordPrivate ( this ) )
{
}
 
Record::~Record()
{
    delete d;
}
 
uint Record::age() const
{
    return d->age();
}
 
QString Record::name() const
{
    return d->name();
}
 
QDataStream& operator<<( QDataStream& dataStream, const RecordPtr record )
{
    for(int i=0; i< record->metaObject()->propertyCount(); ++i) {
        if(record->metaObject()->property(i).isStored(record)) {
            dataStream << record->metaObject()->property(i).read(record);
        }
    }
    return dataStream;
}

#include "record_p.h"

using namespace MyApp;

RecordPrivate::RecordPrivate ( Record* qq, QObject* parent ) :
    QObject ( parent ),
    q ( qq )
{
}

uint RecordPrivate::age() const
{
    return m_age;
}

QString RecordPrivate::name() const
{
    return m_name;
}

Record::Record(QObject *parent) :
    QObject(parent),
    d ( new RecordPrivate ( this ) )
{
}

Record::~Record()
{
    delete d;
}

uint Record::age() const
{
    return d->age();
}

QString Record::name() const
{
    return d->name();
}

QDataStream& operator<<( QDataStream& dataStream, const RecordPtr record )
{
    for(int i=0; i< record->metaObject()->propertyCount(); ++i) {
        if(record->metaObject()->property(i).isStored(record)) {
            dataStream << record->metaObject()->property(i).read(record);
        }
    }
    return dataStream;
}

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record.cpp:-1: In function 'QDataStream& operator<<(QDataStream&, MyApp::RecordPtr)':
no matching function for call to 'QMetaProperty::isStored(const RecordPtr&)'
if(record->metaObject()->property(i).isStored(record)) {
^
candidate is:
bool QMetaProperty::isStored(const QObject*) const
bool isStored(const QObject *obj = 0) const;
^
note: no known conversion for argument 1 from 'const RecordPtr {aka const QSharedPointer<MyApp::Record>}' to 'const QObject*'

Where is my error?

Very thanks.

[anda_skoa]

The compiler already told you the error, didn't it?

no known conversion for argument 1 from 'const RecordPtr {aka const QSharedPointer<MyApp::Record>}' to 'const QObject*'

you are trying to pass an object of type RecordPtr to a method expecting "const QObject*".

Cheers,
_

[jiveaxe]

you are trying to pass an object of type RecordPtr to a method expecting "const QObject*".
_

This is obvious but doesn't help me to track my error. If I use a plain Record class (no pimpl, no shared pointer), the compiler is happy despite passing a Record object. So probably I should "cast" QSharedPointer<MyApp::Record> to Record, but don't know how...

---

Added after 59 minutes:

Ok, solution found; it was easy: QSharedPointer::data ().

This is the correct code:

QDataStream& operator<<( QDataStream& dataStream, const RecordPtr record )
{
    for(int i=0; i< record->metaObject()->propertyCount(); ++i) {
        if(record->metaObject()->property(i).isStored(record.data())) {
            dataStream << record->metaObject()->property(i).read(record.data());
        }
    }
    return dataStream;
}

QDataStream& operator<<( QDataStream& dataStream, const RecordPtr record )
{
    for(int i=0; i< record->metaObject()->propertyCount(); ++i) {
        if(record->metaObject()->property(i).isStored(record.data())) {
            dataStream << record->metaObject()->property(i).read(record.data());
        }
    }
    return dataStream;
}

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