Qlist of qlist

beh_zad

Hi everybody, I created qvariantlist of qvariantlist like this:
@ QVariantList DP;
DP<< 2 << 2300 << 400 << 14.5 << 17.62 << 0 << 0 << 0 << 80;

QVariantList DC;
DC<< 3 << 2700 << 35 << 0 << 21.6 << 21.6 << 0 << 2735 << 0;

QVariantList dataList;
dataList<< DP <<DC  ;@

but my problem is that, when i return the size of the datalist (@qDebug() << dataList.size();@), qdebug shows the number 16, but I want to show 2, because i filled it up with two data :(

dheerendra

In your program third list is not declared properly. I think your idea is to create list of QVariantList. It should be something like the following. Try following.

@ QList<QVariantList> dataList;
dataList<<DP<<DC;
qDebug() << dataList.size();@

beh_zad

thanks, it worked. but if i want to pass it to qml what do i do?

beh_zad

i use it:

@ QQuickView view;

QQmlContext *myList = view.rootContext();
myList->setContextProperty("myList", QVariant::fromValue(dataList));

view.setSource(QUrl("Main.qml"));

view.show();@

but in qml i can't use it, for example @myList [0][0]@

dheerendra

Did you get a chance to look at QQmlListProperty ? This may help you.

beh_zad

is it possible to pass 2d list from c++ to qml ?
when i used @QVariantList dataList;
dataList<< DP <<DC ;@ instead of @QList<QVariantList> dataList;
dataList<<DP<<DC;@ i could to pass it with that codes but in 1d list, for example myList [0] worked but now it doesn't work

Chris Kawa

Guys, read the docs.
<< operator for lists appends list elements, not the lists themselves. If you want to create a list of lists you need to explicitly create a variant from the list, eg.

@
//this appends DP and DC elements to dataList
//size of dataList is size of DP + size of DC
dataList << DP << DC;

//this creates new variants of type "list" and puts them into dataList
//size is 2
dataList << QVariant(DP) << QVariant(DC);
@

Btw. QList<QVariantList> doesn't make sense. QVariantList is a typedef for QList<QVariant> so this gives QList<QList<QVariant>>, and what we want is QList<QVariant> where the inner QVariant holds another QList<QVariant>.

dheerendra

Thanks Chris. It is typedef as well. Based on this only I suggested him. It depends on the requirement on how to make list of list. I have used it where I wanted list of List only. Based on this only I suggested him to create QList of QVariantList. I don't want QList<Variant>.

beh_zad

thanks Chris and Dheerendra. i have done it.