[Solved] QTableWidgetItem obtain value for table cell containing custom class instance

[q456]

I started out with the StarDelegate Item. To simplify the code I have the following class:
@
class StarRating
{
public:
StarRating(int starCount = 1)
{
myStarCount = starCount;
}
int starCount() const
{
return myStarCount;
}
void setStarCount(int starCount)
{
myStarCount = starCount;
}
private:
int myStarCount;
};
Q_DECLARE_METATYPE(StarRating)
#endif
@

And I do this:

@
QTableWidgetItem *item0 = new QTableWidgetItem;
item0->setData(0, qVariantFromValue(StarRating(3)));
@

StarRating is the custom class used by the StarDelegate to display a number as stars, the number of which a user can edit. I connected the SIGNAL (cellChanged(int, int)) to a function using signalMapper, that part works. the problem is I can't access "the value" in the cell. For cells containing strings and ints QTableWidgetItempointer->text()->toInt(); or something like that works. How can I get the value in a cell that contains a custom like StarRating? To I use QTableWidgetItem::Data()? Do I override it somehow?

[Jeroentjehome]

Hi,
NOTE: The qVariantFromValue() function is OBSOLETE in Qt5!!
Use the fromValue() function instead! Read the docs properly.
Non the less, you used the Q_DECLARE_METATYPE so the StarRating is transportable via Signal/Slots. So, in the receiving slot you should be able to get the data from the QVariant via
@T QVariant::value () const@
So code might look like this:
@
StarRating (QVariant::value(QTableWidgetItemPointer);
int MyCount (StarRating.starCount());
@
Not tested, but that might do the trick. What QVariant will probably do in this case is to copy the class that was send to the event queue and hold a pointer to it. The value() function then constructs a class interface via that pointer. In basic that's it.

[frederik]

You can either store raw pointers and static_cast (if you are absolutely sure that all items contain a valid StarDelegate) or qobject_cast them, or you do as suggested above, but you'll need a small fix: it's QVariant::value<StarDelegate>().

[q456]

Thank you for your replies. I tried both approaches but none of them work so far:
@
QTableWidgetItem *item = new QTableWidgetItem;
item->setData(0, QVariant::fromValue(StarRating(3)));
qDebug() << (static_cast<StarRating>(*item)).starCount();
@
No matching function for call to StarRating::StarRating(QTableWidgetItem&)

@
qDebug() << StarRating(QVariant::value<StarRating>(*item)).starCount();
@

No matching function for call to QVariant::value(QTableWidgetItem&)
@
qDebug() << StarRating(QVariant(*item).value()).starCount();
@
No matching function for call to QVariant::QVariant(QTableWidgetItem&);

I used the (*pointer), but the same occurs if I use the pointer itself.

So far, I can put the StarRating into the QTableWidgetItem but I cannot extract the StarRating (or just the value of myStarCount) back from the QTableWidgetItem*.

[SGaist]

Hi,

You are trying to convert a QTableWidgetItem to your StarRating class which is not possible. Your StarRating object is located in the data of the item not the item itself.

Try that:
@StarRating sr = qvariant_cast<StarRating>(item->data(Qt::DisplayRole));@

Edit: corrected code

[q456]

It worked like this (0 reprezents the corresponding user role.) :

@
StarRating sr = qvariant_cast<StarRating>(item->data(0));
qDebug() << sr.starCount();
@

Thank you very much for your help.

[SGaist]

You're welcome !

Indeed, it was a mental typo between QVariant and QTableWidgetItem