[Qt/C++]problem z Undefined reference na konstanti znotraj razreda

#ifndef UEPEOPLEMODEL_H
#define UEPEOPLEMODEL_H

#include <QImage>
#include <QVariant>
#include <QStringList>
#include <QDebug>
#include <QHash>
#include <QByteArray>
#include <QtSql/QSqlError>
#include <QtSql/QSqlQueryModel>
#include <QtSql/QSqlRecord>
#include <QModelIndex>
#include <QQuickImageProvider>

#include "../settings/uedefaults.h"
#include "../settings/uetypes.h"

class UePeopleModel : public QSqlQueryModel, QQuickImageProvider
{
    Q_OBJECT

public:
    UePeopleModel(QObject *parent=0);
    ~UePeopleModel();

    QVariant data(const QModelIndex &index,
                  int role) const Q_DECL_OVERRIDE;
    QImage image(const QString &id) const;
    QImage requestImage(const QString &id,
                        QSize *size,
                        const QSize &requestedSize);
    UeTypeRoles roleNames() const;

public:
    static const int UePersonNameRole=0x101;//Qt::UserRole+1;/*0x0101;*/
    //static const int UePersonImageRole=UePersonNameRole+1;/*0x0102;*/
    //static const int UePersonImageRole=Qt::UserRole+2;
};

#endif // UEPEOPLEMODEL_H

#include "uepeoplemodel.h"

UePeopleModel::UePeopleModel(QObject* parent)
    : QSqlQueryModel(parent),
      QQuickImageProvider(QQmlImageProviderBase::Image,
                          QQmlImageProviderBase::ForceAsynchronousImageLoading)
{
    QSqlDatabase db;

    if(!QSqlDatabase::connectionNames().contains(UePosDatabase::UeDatabaseConnectionNames::DATABASE_CONNECTION_NAME_PEOPLE,
                                                 Qt::CaseInsensitive))
    {
            db=QSqlDatabase::addDatabase(UePosDatabase::DATABASE_DRIVER,
                                         UePosDatabase::UeDatabaseConnectionNames::DATABASE_CONNECTION_NAME_PEOPLE);
    }   // if

    db.setHostName(/*this->uePosSettings()->ueDbHostname()*/UePosDatabase::UeDatabaseConnectionParameters::DATABASE_HOSTNAME);
    db.setDatabaseName(/*this->uePosSettings()->ueDbName()*/UePosDatabase::UeDatabaseConnectionParameters::DATABASE_NAME);
    db.setUserName(/*this->uePosSettings()->ueDbUser()*/UePosDatabase::UeDatabaseConnectionParameters::DATABASE_USERNAME);
    db.setPassword(/*this->uePosSettings()->ueDbPassword()*/UePosDatabase::UeDatabaseConnectionParameters::DATABASE_PASSWORD);

    if(db.open())
    {
        this->setQuery(UePosDatabase::UeSqlQueries::UeTablePeople::SQL_QUERY_GET_ALL_PEOPLE,
                       db);
    }
    else
    {
        qDebug() << db.lastError().text();
    }
}   // default constructor

UePeopleModel::~UePeopleModel()
{
}   // default destructor

QVariant UePeopleModel::data(const QModelIndex &index,
                             int role) const
{
    QVariant value=QSqlQueryModel::data(index,
                                        role);
    if(value.isValid())
    {
        switch(role)
        {
        case UePeopleModel::UePersonNameRole:
            {
                return value.toString();
            }   // case

/*
        case UePeopleModel::UePersonImageRole:
            {
                return QString::number(index.row());
            }   // case
*/

            default:
                value=QVariant();
        }   // switch
    }   // if

    return value;
}   // data

QImage UePeopleModel::image(const QString &id) const
{
    int iRow=id.toInt();
}   // image

QImage UePeopleModel::requestImage(const QString &id,
                                   QSize *size,
                                   const QSize &requestedSize)
{
    QImage image=this->image(id);

    *size = image.size();

    return image;
}   // requestImage

UeTypeRoles UePeopleModel::roleNames() const
{
    UeTypeRoles roles;

    roles.insert(UePersonNameRole,
                 "UePersonNameRole");
/*
    roles.insert("UePersonImageRole",
                 UePersonNameRole);
*/

    return roles;
}   // roleNames

roles.insert(UePersonNameRole,
"UePersonNameRole");

uepeoplemodel.cpp:87: error: undefined reference to `UePeopleModel::UePersonNameRole'

stapler rump je 19. avg 2015 ob 10:57 izjavil:

Tole si preberi.

Jeremias je 19. avg 2015 ob 11:34 izjavil:

Na hitro. Predvidevam da tvoja funkcija deklarirana kot UeTypeRoles::insert(const int &type, String &name) oz. nekaj podobnega. No problem pri tebi je, da funkcija za prvi parameter pričakuje referenco, ker pa ti imaš UePersonNameRole spremenljivko deklarirano kot static (katero kompajler zamenja z dejansko vrednostjo ob prevajajnju) ti ne more podat kot referenco in zaradi tega dobiš error. Možnosti imaš tu dve, umakneš static od spremenljivke ali pa enostavno spremeniš funkcijo insert da sprejema int namesto referenco na int.

UeTypeRoles UePeopleModel::roleNames() const
{
    UeTypeRoles roles;

    roles.insert(0x0101,
                 "UePersonNameRole");
    roles.insert(0x0102,
                 "UePersonImageRole");

    return roles;
}   // roleNames

typedef QHash<int, QByteArray> UeTypeRoles;

windigo je 19. avg 2015 ob 12:22 izjavil:

Tako, kot so ti napisali: QHash::insert(const Key & key, const T & value) jemlje reference, ne vrednosti, kompajler pa reference sploh nima, ker se je pisec kompajlerja odločil, da bo v takem primeru povsod po kodi raje vstavil neposredno vrednost in ne bo alociral prostora za statično spremenljivko (saj gre za konstanto), tukaj zato ne more narediti reference.

Workaround je simpl:

const int myRole = UePersonRoleName;
roles.insert(myRole, "bla bla");