Disable Qt::CheckStateRole

ochampao

I am developing a custom model derived from QAbstractTableModel. The model re-implements the data(), setData() and flags() methods as follows:

QVariant TableModel::data(const QModelIndex &index, int role) const
{
	if (!index.isValid())
		return QVariant();

	// get the coordinates of the item
	int row = index.row();
	int col = index.column();

	// load the record pointed to by the row index for the current query
	Record recordLoaded = mDao->readRecordN(row, mCurrentQuery);

	// handle the different roles
	switch (role)
	{
	case Qt::DisplayRole:
		return readDisplayRoleData(col, recordLoaded);
	
	case Qt::EditRole:
		return readEditRoleData(col, recordLoaded);

	case Qt::BackgroundRole:
		return readBackgroundRole(col, recordLoaded);

	case Qt::CheckStateRole:
		return readCheckStateRoleData(col, recordLoaded);

	default:
		break;
	}

	return QVariant();
}

bool TableModel::setData(const QModelIndex & index, const QVariant & value, int role)
{
	if (!index.isValid())
		return false;

	// get the coordinates of the item to be edited
	int row = index.row();
	int col = index.column();

	// load record to be edited
	Record recordEdited = mDao->readRecordN(row, mCurrentQuery);

	switch (role)
	{
	case Qt::EditRole:
	if (writeEditRoleData(col, recordEdited, value))
	{
		mDao->updateRecord(recordEdited);

		// notify the view for the changes
		emit dataChanged(index, index);

		return true;
	}
	case Qt::BackgroundRole:
	if (writeBackgroundRole(col, recordEdited, value))
	{
		// notify the view for the changes
		emit dataChanged(index, index);

		return true;
	}
	case Qt::CheckStateRole:
	if (writeCheckStateRoleData(col, recordEdited, value))
	{
		// notify the view for the changes
		emit dataChanged(index, index);
		
		return true;
		}
	default:
		break;
	}

	return false;

}

Qt::ItemFlags TableModel::flags(const QModelIndex& index) const
{
	if (!index.isValid())
		return Qt::ItemIsEnabled;

	int columnId = index.column();
	 
	switch (columnId)
	{
	case TableModel::Column1:
	case TableModel::Column2:
	case TableModel::Column3:
	case TableModel::Column4:
	default:
	  return QAbstractItemModel::flags(index);
		break;
	}
}

It is also important to note how the two methods readCheckStateRoleData() and writeCheckStateRoleData() are implemented:

QVariant TableModel::readCheckStateRoleData(int columnId, Record& record) const
{
	switch (columnId)
	{
	case TableModel::Column1:
	{
		bool isVisible2D = false;
		
		// Some code to read value of isVisible2D

		return (isVisible2D ? Qt::Checked : Qt::Unchecked);
	}
	case TableModel::Column2:
	{
		bool isVisible3D = false;
		
		// some code to read value of isVisible3D
		
		return (isVisible3D ? Qt::Checked : Qt::Unchecked);
	}
	case TableModel::Column3:
	case TableModel::Column4:
	default:
		return QVariant();
	}
}

bool TableModel::writeCheckStateRoleData(int columnId, PlanImageRecord& record, const QVariant& value)
{
	switch (columnId)
	{
	case TableModel::Column1:
	{	
		bool isChecked = false;
		if ((Qt::CheckState)value.toInt() == Qt::Checked)
			isChecked = true;

		// code to save value in database
		return true;
	}
	case TableModel::Column2:
	{
		bool isChecked = false;
		if ((Qt::CheckState)value.toInt() == Qt::Checked)
			isChecked = true;

		// code to write new value in database
		return true;
	}
	case TableModel::Column3:
	case TableModel::Column4:
	default:
		return false;
	}
}

The problem that I have is that although the flags() method for Column1 and Column2 does not set the flag Qt::ItemIsUserCheckable, the items of these columns appear as checkboxes. How can I avoid this while still handling the Qt::CheckStateRole role in the data() and setData() methods? Is this possible?

The reason why I am trying to keep handling the Qt::CheckStateRole is because I am displaying the same model in two separate QTableView's but in the second view the model is wrapped in a proxy model which modifies the flags such that the columns are editable or displayed as check-boxes where appropriate. In the first view, I only want the DisplayRole of the items to be shown.

Christian Ehrlicher

@ochampao said in Disable Qt::CheckStateRole:

Is this possible?

No since you return valid values for the Qt::CheckStateRole for those columns. When you don't want checkboxes then don't return a valid value for them.
The flag only defines if the use is able to modify the check state or not.

ochampao

Thank you for your reply!

So the only way that I can achieve what I am trying to do is using a custom Delegate? Is there an alternative to implementing a delegate?

Thanks.

Christian Ehrlicher

You can use a QIdentityProxyModel