[Qt-interest] QVariant conversion problem

[Sean Harmer]

Hi,

Stephen Collyer wrote:
> I have some code where the relevant defns are as follows:
> 
> const QList<quint32> storytranslation_ids_by_lang
> 
> QMap<QString, QVariant>   where_data;
> where_data["fk_storytranslation_id"] = 
> QVariant(storytranslation_ids_by_lang);
> 
> g++ is complaining about the assignment in the final line, with the
> following message:
> 
> error: no matching function for call to ?QVariant::QVariant(const 
> QList<unsigned int>&)?
> /usr/local/Trolltech/Qt-4.6.1/include/QtCore/qvariant.h:432: note: 
> candidates are: QVariant::QVariant(bool, int)
> /usr/local/Trolltech/Qt-4.6.1/include/QtCore/qvariant.h:425: 
> note:                 QVariant::QVariant(void*)
> /usr/local/Trolltech/Qt-4.6.1/include/QtCore/qvariant.h:222: 
> note:                 QVariant::QVariant(Qt::GlobalColor)
> 
> <etc>
> 
> I can't see why, as there is a QVariant ctor as follows:
> 
> *QVariant* ( const QList<QVariant> & /val/ )
> 
> Can someone suggest what I'm missing ?

You need to put your data into a QVariant first. There is no QVariant 
constructor that takes your type, so you need something like:

const QList<quint32> storytranslation_ids_by_lang
QMap<QString, QVariant>   where_data;
QVariant v;
v.setValue(storytranslation_ids_by_lang);
where_data["fk_storytranslation_id"] = v;

Note that you also need to tell QMetaType about your new type that you 
wish to store within QVariant too. You can do this with the 
Q_DECLARE_METATYPE() macro.

Cheers,

Sean