Qtableview delegate

[n-2204]

Hi,
I'm using Qtableview (QStandardItemModel ) and i used delegate in columns so only double type data is used, so its working but one issue is when i'm try to del data from my columns which i used delegate then its not deleting i can change the data why not delete happening ?
shared the code--

#include< QStyledItemDelegate>
class IntDelegate : public QStyledItemDelegate
{
 public:
 IntDelegate(QObject* parent = 0);
QWidget* createEditor(QWidget* parent, const QStyleOptionViewItem& option, 
const QModelIndex& index) const;
void setEditorData(QWidget* editor, const QModelIndex& index) const;
void setModelData(QWidget* editor, QAbstractItemModel* model, const QModelIndex& index) const;
void updateEditorGeometry(QWidget* editor, const QStyleOptionViewItem& 
option, const QModelIndex& index) const;
 private:
 };
//cpp file
#include "IntDelegate.h"
#include <QDoubleValidator>
 IntDelegate::IntDelegate(QObject* parent) :QStyledItemDelegate(parent)
 {
 }
QWidget* IntDelegate::createEditor(QWidget* parent, const 
QStyleOptionViewItem& option, const QModelIndex& index) const
{
QLineEdit* editor = new QLineEdit(parent);
editor->setValidator(new QDoubleValidator);
return editor;
}
void IntDelegate::setEditorData(QWidget* editor, const QModelIndex& index) 
 const
  {
double value = index.model()->data(index, Qt::EditRole).toDouble();
QLineEdit* line = static_cast<QLineEdit*>(editor);
line->setText(QString().setNum(value));
}
void IntDelegate::setModelData(QWidget* editor, QAbstractItemModel* model, 
const QModelIndex& index) const
{
QLineEdit* line = static_cast<QLineEdit*>(editor);
QString value = line->text();
model->setData(index, value);
  }
 void IntDelegate::updateEditorGeometry(QWidget* editor, const 
QStyleOptionViewItem& option, const QModelIndex& index) const
{
editor->setGeometry(option.rect);
}
//use 
 IntDelegate* intdelegate;
 intdelegate = new IntDelegate();
ui.tableView->setItemDelegateForColumn(5, intdelegate);
ui.tableView->setItemDelegateForColumn(4, intdelegate);
ui.tableView->setItemDelegateForColumn(8, intdelegate);

Any change req. in delegate file ? or I done something wrong ?

[VRonin]

Because an empty string is not a vaid double.

Change editor->setValidator(new QDoubleValidator); to

const QRegularExpression doubleExpression(QStringLiteral(R"***(^(?:[-+]?\d*%1?\d+(?:%2[-+]?\d+)?)?$)***")
    .arg(QString(QRegularExpression::escape(editor->locale().decimalPoint())),QString(QRegularExpression::escape(editor->locale().exponential()))),QRegularExpression::CaseInsensitiveOption);
editor->setValidator(new QRegularExpressionValidator(doubleExpression,editor));

Few other fixes:

• in setEditorData, line->setText(QString().setNum(value)); should become line->setText(line->locale().toString(value)); to work on languages that use different decimal separators from the USA
• in setModelData, QString value = line->text(); model->setData(index, value); should become model->setData(index, line->locale().toDouble(line->text())); to store the numbers as numbers and not strings

[n-2204]

Thanku , is any other chnage in code you shared bcz i'm getting error

     QWidget* IntDelegate::createEditor(QWidget* parent, const 
     QStyleOptionViewItem& option, const QModelIndex& index) const
    {
	QLineEdit* editor = new QLineEdit(parent);
     const QRegularExpression doubleExpression(QStringLiteral(R"***(^(?:[-+]?\d*%1?\d+(?:%2[-+]?\d+)?)?$)***")
    .arg(QString(QRegularExpression::escape(locale().decimalPoint())), QS 
     tring(QRegularExpression::escape(locale().exponential()))), 
    QRegularExpression::CaseInsensitiveOption);
	editor->setValidator(new QRegularExpressionValidator(doubleExpression, editor));
	return editor;
//here getting  error identifier locale is undefined

    }
     void IntDelegate::setEditorData(QWidget* editor, const QModelIndex& index) const
    {
	double value = index.model()->data(index, Qt::EditRole).toDouble();
	QLineEdit* line = static_cast<QLineEdit*>(editor);
	line->setText(line->locale().toString(value));
    } 
     void IntDelegate::setModelData(QWidget* editor, QAbstractItemModel* model, 
    const QModelIndex& index) const
     {
	QLineEdit* line = static_cast<QLineEdit*>(editor);
	QString value = line->text();
	model->setData(line->locale().toDouble(line->text()), value);
//error on line no suitable constructor exists to convert from "double" to "QModelIndex"

     }

[VRonin]

They are both just silly things. I corrected the previous post

[n-2204]

ok,,but using this code whats happening is when i click on cell (in column where delegate applied) but i will not enter data then also it will set to cell data to 0.
can't be possible to leave empty ?

[VRonin]

sure.
instead of model->setData(index, line->locale().toDouble(line->text()));
put

if(line->text().isEmpty())
model->setData(index,QVariant())
else
model->setData(index, line->locale().toDouble(line->text()));

[n-2204]

Ok Thankyou

[JoeCFD]

@VRonin QString().setNum(value) ==>QString::number( value ) is ok as well.

[VRonin]

@JoeCFD nope! In most of Europe, for example, the decimal part follows ,, QString::number will fail in that case. Always use QLocale when dealing with things presented to the user