Boolean values and Qt roles in models

andi456

Hi,

as far as i understand it, if the role Qt::CheckStateRole is not used in the data method of a QAbstractTableModel a boolean value would be displayed as string (true/false). With the additional Qt::CheckStateRole i managed to get a default CheckBox alongside with string representation of the boolean value. The corresponding column is set to be editable and checkable. So now i can alter the string representation but the CheckBox does not respond to user input, although the Qt::ItemIsUserCheckable is set in the flags method too. Are those flags mutually exclusive in that way?

Christian Ehrlicher

Do you properly handle Qt::CheckStateRole in your setData() function?

VRonin

Also, Qt::CheckStateRole does not expect a boolean but a Qt::CheckState

andi456

@Christian-Ehrlicher

} else if (role==Qt::CheckStateRole) {

          int zeile,
                  spalte;
          zeile = index.row();
          spalte = index.column();
         nlohmann::json row_obj = ZTableModel::get_row_obj(zeile);
         QList<QString> headerliste = ZTableModel::get_header(j_zl);
         for (int i=0; i<headerliste.size(); ++i) {
            if (i == spalte) {
                QString qs = headerliste.at(i);
                std::string spaltenname = qs.toStdString();
                QVariant qvtest = value;
                if ((value.canConvert<bool>()) && (qvtest.convert(QVariant::Bool))) {
                    bool neuerboolwert = value.toBool();
                    row_obj[spaltenname] = neuerboolwert;
                }
            }

        }
   emit dataChanged(index, index);
   return true;

This is the part of the setData() function, that should handle Qt::CheckStateRole. If it is inappropriate for boolean values, i wonder which role should be used instead.

Christian Ehrlicher

@andi456 said in Boolean values and Qt roles in models:

i wonder which role should be used instead.

Read the post from @VRonin or the documentation: "This role is used to obtain the checked state of an item. (Qt::CheckState)"

VRonin

@andi456 said in Boolean values and Qt roles in models:

for (int i=0; i<headerliste.size(); ++i) {
if (i == spalte)

Why are you iterating?

if ((value.canConvert<bool>()) && (qvtest.convert(QVariant::Bool)))

As mentioned Qt::CheckStateRole does not take a bool. When you click on the checkbox value will contain Qt::Checked that equals 2.

andi456

@VRonin You're right, the iteration is unnecessary.. I will correct that and see, if it changes something and write the code to convert the Qt::Checked value to boolean and for the data() function too.

andi456

            int zeile,
                  spalte;
            zeile = index.row();
            spalte = index.column();
            nlohmann::json row_obj = ZTableModel::get_row_obj(zeile);
            QList<QString> headerliste = ZTableModel::get_header(j_zl);
            QString qs = headerliste.at(spalte);
            std::string spaltenname = qs.toStdString();
            QVariant qvtest = value;
            bool neuerboolwert;
            if ((value.canConvert<int>()) && (qvtest.convert(QVariant::Int))) {
                int checker = value.toInt();
                if (checker==Qt::Checked) {
                    neuerboolwert = true;
                    std::cout << "Checked" << std::endl;
                    row_obj[spaltenname] = neuerboolwert;
                    //code to update the data structure
                } else {
                    neuerboolwert = false;
                    std::cout << "UnChecked" << std::endl;
                    row_obj[spaltenname] = neuerboolwert;
                   //code to update the data structure
                    }
                }

   emit dataChanged(index, index);
   return true;

Seems to work with the corresponding code to set Qt::Checked/Qt::Unchecked values on the data() function. Anyway, I'll disable the editable flag for boolean values, because i can still enter text to the right of checkbox, which overrides it (the checkbox).

Thanks for your support.

Kind regards,

Andreas

VRonin

@andi456 said in Boolean values and Qt roles in models:

i can still enter text to the right of checkbox, which overrides it (the checkbox).

If this happens it's a bug in your setData/data implementation

Christian Ehrlicher

@VRonin said in Boolean values and Qt roles in models:

If this happens it's a bug in your setData/data implementation

And flags() - it returns Qt::ItemIsEditable