How to provide an empty row in QTableView

[Mark81]

In my Qt 6.8.0 application I display a SQlite table:

// ...open db and create tables
QSqlTableModel *_model;

QSqlDatabase db = QSqlDatabase::database("mydb");
_model = new QSqlTableModel(this, db);
_model->setTable("mytable");
_model->setEditStrategy(QSqlTableModel::OnRowChange);
_model->select();

I want to provide an empty row at the end of the table to let the user to add a new record without using a QPushButton.
Something like:

_model->insertRows(_model->rowCount(), 1);

that leads to:

Of course this does not work as expected since the record is already in edit mode. Until I insert a valid data I cannot edit other rows.

Please note that my tables have not null keys, so I can't just add and save an empty record.

[SGaist]

Hi,

One possible way is to use a proxy model that returns the number of rows + 1 and when editing that row, calls whatever is necessary to create the row before adding data to it.

[Mark81]

@SGaist actually, I already have a proxy model:

QSqlTableModel *_model;
QSortFilterProxyModel *_proxyModel;

QSqlDatabase db = QSqlDatabase::database("mydb");
_model = new QSqlTableModel(this, db);
_model->setTable("mytable");
_model->setEditStrategy(QSqlTableModel::OnRowChange);
_model->select();

_proxyModel = new QSortFilterProxyModel(this);
_proxyModel->setSourceModel(_model);
_proxyModel->sort(1);

ui->table->setModel(_proxyModel);

is there a way to use this proxy to do what you suggested or I have to create a new subclass of QSortFilterProxyModel which in turn inherits QAbstractProxyModel?

[JonB]

@Mark81
You could subclass, so _proxyModel = new SubClassedSortFilterProxyModel(this);, and implement the extra row there. But I think I'd leave that as-is because it's useful, and interpose a new QIdentityModel-subclass on top of it to just provide the dummy row for editing when required.

[Mark81]

@JonB yeah, it works. Basically I did the following:

class AddIdentityProxyModel : public QIdentityProxyModel
{
public:
    AddIdentityProxyModel(QObject *parent = 0): QIdentityProxyModel(parent)
    {
    }

    int rowCount(const QModelIndex &parent = QModelIndex()) const
    {
        return sourceModel()->rowCount() + 1;
    }
};

then

QSqlTableModel *_model;
QSortFilterProxyModel *_proxyModel;
AddIdentityProxyModel *_addProxy;

QSqlDatabase db = QSqlDatabase::database("mydb");
_model = new QSqlTableModel(this, db);
_model->setTable("mytable");
_model->setEditStrategy(QSqlTableModel::OnRowChange);
_model->select();

_proxyModel = new QSortFilterProxyModel(this);
_proxyModel->setSourceModel(_model);
_proxyModel->sort(1);

_addProxy = new AddIdentityProxyModel(this);
_addProxy->setSourceModel(_proxyModel);

ui->table->setModel(_addProxy);

it needs some tweaks in order to be fully functional, but I think it could work!