How to apply and view user roles? - qt

Question

I'm trying to create custom model, and want it to work with custom roles. But I dont really understand how to do it. Also, i want to use my model with a qt widget, not with QML View. How roles are applying to certain items?
How to setup ListView, so that could work with my custom roles?
I know that I need to create enum, and reimplement roleNames function
my model .h file
class ListModel : public QAbstractListModel
{
Q_OBJECT
Q_PROPERTY(int count READ count NOTIFY countChanged)
public:
ListModel();
virtual ~ListModel() override;
enum CustomRoles{
RoleType=Qt::UserRole+1,
ButtonRole,
CheckboxRole,
};
protected:
QList<BaseItems*> itemList;
QHash<int, QByteArray> _roles;
// int _RowCount = 0;
public:
void Add(BaseItems* item);
BaseItems* getItem(int index);
void clear();
int count() const;
int rowCount(const QModelIndex &parent = QModelIndex()) const override;
QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const override;
QHash<int, QByteArray> roleNames() const override;
Q_SIGNALS:
void countChanged();
};
my model .cpp file
ListModel::ListModel() : QAbstractListModel()
{
}
ListModel::~ListModel()
{
itemList.clear();
}
void ListModel::Add(BaseItems *item)
{
beginInsertRows(QModelIndex(),itemList.count(),itemList.count());
itemList.append(item);
endInsertRows();
Q_EMIT countChanged();
}
BaseItems* ListModel::getItem(int index)
{
return itemList.at(index);
}
void ListModel::clear()
{
qDeleteAll(itemList);
itemList.clear();
}
int ListModel::count() const
{
return rowCount();
}
int ListModel::rowCount(const QModelIndex &parent) const
{
Q_UNUSED(parent)
return itemList.count();
}
QVariant ListModel::data(const QModelIndex &index, int role) const
{
ItemButton *button = dynamic_cast<ItemButton*>(itemList.at(index.row()));
if (!index.isValid())
return QVariant();
if (index.row() >= itemList.count())
return QVariant();
switch (role)
{
case Qt::DisplayRole:{
return QVariant::fromValue(button->Text);}
case ButtonRole:{
return QVariant::fromValue(button->Text);}
}
return QVariant();
}
QHash<int, QByteArray> ListModel::roleNames() const {
QHash<int, QByteArray> role;
role[RoleType] = "first";
role[ButtonRole] = "last";
return role;
}

Answer 1

Instead of "first" and "last" better you name the roles meaningfully:
QHash<int, QByteArray> ListModel::roleNames() const {
QHash<int, QByteArray> role;
role[RoleType] = "roleType";
role[ButtonRole] = "buttonRole";
return role;
}
So these quoted names will be used. If you want to display the data from this model in QML you can do something like this:
ListView {
width: 100
height: 500
model: listModel
delegate: Text {
text: model.roleType + model.buttonRole
}
}
listModel object can be initialized in C++ and can be passed to QML using
view->rootContext()->setContextProperty("listModel", listModel);
or you can make an instance of the ListModel in QML, but in the cpp file you will have to register your ListModel type
qmlRegisterType<ListModel>("ListModel", 1, 0, "ListModel");
then in the qml file:
import ListModel 1.0
finally creating an instance of the model by
ListModel {
id: listModel
}