Model/view, apply a filter on model

Hello,

I am subclassing QSqlTableModel for a model used by a QListView.
This model represents data stored in a SQLite database.
In this database I have a flag field (let say an int field at column 0).
I want my model to present data depending on the flag value, in other word I want to apply a filter on my model.
So I have a public method setFilter(int flag) to set the current filter on flag value, and I want my model to present only the data (rows) that match this value.

Let say my db is like:

Quote:

---

flag | value
0 | foo
1 | bar

---

After setFilter(0) I want my model to present only:

Quote:

---

flag | value
0 | foo

---

The code :

Code:

---

MyModel::MyModel(QObject *parent) :
    QSqlTableModel(parent),
{
    setTable("myTable");
    select();
}
 
void
MyModel::setFilter(int flag) 
{
currentFlag = flag; // currentFlag is MyModel class member
}
 
QVariant
MyModel::data(const QModelIndex & index, int role ) const
{
    if( index.model()->data(index.sibling(index.row(),0)) == currentFlag) // if the current index points to a row with flag column equals to the current filter, return the value, but this leads to infinite recursive call 
        return QSqlTableModel::data(index, role);
    else return QVariant(); // else return an invalid data
}

---

Problem is, to check the flag value I have to call data() inside the data() method, which leads to infinite recursive call.
How can I solve this ? How can I check value of another ModelIndex in the QAbstractItemModel::data() method ? Is it possible or am I using Model/view classes the wrong way ?

Hope everything is clear.

Hi, you can try a proxy model (like QSortfilterProxyModel). The proxy model will check the flag, the normal model underneath will provide the data.

Ginsengelf

Use QSqlTableModel::setFilter().

For example

Code:

---

void
MyModel::setFilter(int flag) 
{
  QString filterString (QString ("flag=%1").arg(flag));
  this->setFilter (filterString);
  select();
}

---

Thanks ! both work !

The solution of Ginsengelf it's good and it's more general than mine.

When you use an HUGE Database, probably, my solution is faster because the sorting/filtering phase it's optimized in SQL engines.