Validator for QDoubleSpinBox

[ehamberg]

Hi,

I have a QTableView with a QAbstractTableModel and a custom delegate for editing the different fields. For one of the fields I have a QDoubleSpinBox and I want to change the default validator to allow both a comma and a dot to be used as a decimal symbol. However the lineEdit() methond in QDoubleSpinBox is protected, so I get an error. What is the easiest way I can change the spinbox' validator?

The code:

void ExpensesDelegate::setEditorData(QWidget *editor, const QModelIndex &index) const
{
    if (index.column() == AMOUNT_COLUMN) {
        QDoubleSpinBox *amountEditor = qobject_cast<QDoubleSpinBox *>(editor);
 
        amountEditor->lineEdit()->setValidator(new QRegExpValidator(QRegExp("-?[0-9]*[.,]?[0-9]*"), amountEditor)); // <---
 
        amountEditor->setValue(index.model()->data(index, Qt::EditRole).toDouble());
 
...

void ExpensesDelegate::setEditorData(QWidget *editor, const QModelIndex &index) const
{
    if (index.column() == AMOUNT_COLUMN) {
        QDoubleSpinBox *amountEditor = qobject_cast<QDoubleSpinBox *>(editor);

        amountEditor->lineEdit()->setValidator(new QRegExpValidator(QRegExp("-?[0-9]*[.,]?[0-9]*"), amountEditor)); // <---

        amountEditor->setValue(index.model()->data(index, Qt::EditRole).toDouble());

...

To copy to clipboard, switch view to plain text mode 

[jpn]

Hmm, at least you can use QObject::findChild() to get around the limitation.

[wysota]

I think changing the validator is not enough. The spinbox has its own internal validation method - valueFromText. It's enough if you reimplement it and convert the text to double there, no need for a validator.

[ehamberg]

I think changing the validator is not enough. The spinbox has its own internal validation method - valueFromText. It's enough if you reimplement it and convert the text to double there, no need for a validator.

The problem is just that without altering the validator, one can't type a comma. Here's the solution I ended up with:

class AmountSpinBox : public QDoubleSpinBox
{
    Q_OBJECT
 
public:
    AmountSpinBox(QWidget *parent = 0) : QDoubleSpinBox(parent)
    {
        m_decimalSymbol = KGlobal::locale()->monetaryDecimalSymbol();
 
        // regexp for the validator:
        // 1) optional minus sign then 0 or more digits
        // 2) dot or locale decimal symbol
        // 3) 0, 1 or 2 digits
        lineEdit()->setValidator(new QRegExpValidator(QRegExp("-?[0-9]*[." +
                        (m_decimalSymbol != "." ? m_decimalSymbol : "") // add locale deciman symbol if it's not a dot
                        + "]?[0-9]{,2}"), this));
 
        setAlignment(Qt::AlignRight);
        setButtonSymbols(QDoubleSpinBox::PlusMinus);
        setRange(-9999999999.99, 9999999999.99);
    }
 
private:
    double valueFromText(const QString &text) const
    {
        QString m_decimalSymbol = KGlobal::locale()->monetaryDecimalSymbol();
        QString temp = text;
        temp.replace(QRegExp(m_decimalSymbol), "."); // replace locale decimal symbol with dot before toDouble()
 
        return temp.toDouble();
    }
 
    QValidator::State validate ( QString & input, int & pos ) const
    {
        // let's *really* trust the validator :-)
        return QValidator::Acceptable;
    }
 
    QString m_decimalSymbol;
};

class AmountSpinBox : public QDoubleSpinBox
{
    Q_OBJECT

public:
    AmountSpinBox(QWidget *parent = 0) : QDoubleSpinBox(parent)
    {
        m_decimalSymbol = KGlobal::locale()->monetaryDecimalSymbol();

        // regexp for the validator:
        // 1) optional minus sign then 0 or more digits
        // 2) dot or locale decimal symbol
        // 3) 0, 1 or 2 digits
        lineEdit()->setValidator(new QRegExpValidator(QRegExp("-?[0-9]*[." +
                        (m_decimalSymbol != "." ? m_decimalSymbol : "") // add locale deciman symbol if it's not a dot
                        + "]?[0-9]{,2}"), this));

        setAlignment(Qt::AlignRight);
        setButtonSymbols(QDoubleSpinBox::PlusMinus);
        setRange(-9999999999.99, 9999999999.99);
    }

private:
    double valueFromText(const QString &text) const
    {
        QString m_decimalSymbol = KGlobal::locale()->monetaryDecimalSymbol();
        QString temp = text;
        temp.replace(QRegExp(m_decimalSymbol), "."); // replace locale decimal symbol with dot before toDouble()

        return temp.toDouble();
    }

    QValidator::State validate ( QString & input, int & pos ) const
    {
        // let's *really* trust the validator :-)
        return QValidator::Acceptable;
    }

    QString m_decimalSymbol;
};

To copy to clipboard, switch view to plain text mode