6

I have a QTableView connected with an QSqlTableModel.
In the first column, there are only dates at this format: 2010-01-02
I want this column to show the date at this format (but without changing the real data): 02.01.2010
I know that I have to create an QItemDelegate for this column, but I don't know how I can read the existing data and overwrite it with something different. You have any idea how to manage that?

Berschi
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2 Answers2

15

The simplest solution is to create a QStyledItemDelegate subclass and reimplement displayText(...) ie

class DateFormatDelegate : public QStyledItemDelegate
{
public:
 DateFormatDelegate (QString dateFormat, QObject *parent = 0) : 
  QStyledItemDelegate(parent),
  m_dateFormat(dateFormat)
 {
 }

 virtual QString displayText(const QVariant & value, const QLocale & locale ) const
 {
  Q_UNUSED(locale);
  return value.toDate().toString(m_dateFormat);
 }

private:
 QString m_dateFormat;
};

Then in your view - 

setItemDelegateForColumn(/*date column*/, new DateFormatDelegate("MM.dd.yyyy", this));
sth
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Noah
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4

An item delegate doesn't necessarily change the data, it just renders the data. Also, if you're using Qt 4.4 or newer, look at QStyledItemDelegate instead--it's theme-aware and will look nicer.

There's an example of item delegates in this article (which seems to be a mirror of official documentation that is now down or gone).

Since all you really want to do is customize the text, have you considered using a proxy model instead and just returning your custom QString for the date column's DisplayRole?

George Hilliard
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ChrisV
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  • Either the delegate or the proxy model would work pretty well in this situation. The delegate is probably closer to what what intended, however. – Caleb Huitt - cjhuitt Jan 06 '10 at 17:26
  • my problem is, that i don't get how to make it with an QItemDelegate. the paint()-method will not work for me – Berschi Jan 07 '10 at 02:31
  • What, specifically, is the problem with paint()? – ChrisV Jan 07 '10 at 02:43
  • i know how to get the data ( qVariantValue(index.data()) ), but i don't know how to overwrite it with "foo" for example – Berschi Jan 07 '10 at 14:34
  • This is where using a proxy model will come in handy, as it's easier to support row/column/type-specific hacks there, but since you apparently really want a delegate... Create a QStyledItemDelegate subclass which reimplements paint() and sizeHint(). These implementations should actually check whether index.data() returns a QDate in the variant; if not, they should just call the base class's implementation. If so, do your own string conversion and either measure it (for sizeHint()) or draw it (for paint()). – ChrisV Jan 07 '10 at 19:39