Drag and drop to a Pushbutton

dencla

@JonB I have both, it is when I have created the view with a queryModel that it does not work. Are you saying that it is because it is a query model that it is not working? It allows me to create a call to a query model to insert a row.

    QSqlTableModel tmodel;
    tmodel.insertRows(0,1,QModelIndex());

    QSqlQueryModel qmodel;
    qmodel.insertRows(0,1,QModelIndex());

It would make sense if that is the case, so why can I create the call.

JonB

@dencla
insertRows() returns a bool result, why don't you print that out? Being able to call something from C++ versus what result it might return if it does not work are two different things.

https://doc.qt.io/qt-6/qabstractitemmodel.html#insertRows

On models that support this, inserts count rows into the model before the given row.

Returns true if the rows were successfully inserted; otherwise returns false.

https://doc.qt.io/qt-6/qsqlquerymodel.html

The QSqlQueryModel class provides a read-only data model for SQL result sets.

https://doc.qt.io/qt-6/qsqltablemodel.html

The QSqlTableModel class provides an editable data model for a single database table.

What would be the point of alteration or drag and drop into for a QSqlQueryModel?

dencla

@JonB I think that you are correct. It does return false for the qmodel. so why does the query model allow calls to edit it?

dencla

@JonB Which brings me to the reason for using the queryModel. When I create a ui->CustomTableView nothing is displayed, but when I create a normal tableView it does display the database.

JonB

@dencla said in Drag and drop to a Pushbutton:

so why does the query model allow calls to edit it?

Because QSqlQueryModel is derived from QAbstractTableModel if you are asking about compilation. At runtime we have already said it returns an unsuccessful result if you call it. Some model types allow editing, some do not.

When I create a ui->CustomTableView nothing is displayed, but when I create a normal tableView it does display the database.

I don't know what this means. If a QTableView works but a CustomTableView derived from that does not look at your code differences in the custom view. I don't know what this has to do with QSqlQueryModel vs QSqlTableModel, nor with drag and drop.

dencla

@JonB It does not have a direct reason for drag and drop. When I was working on my CustomSqlTableView drag and drop works when I called it directly in the example but when I tried to promote it to a CustomSqlTableView it does not display in a ui->table view, but a CustomQueryModel does, but does not work.

So I'm back to figuring out why, so I can drag to a pushbutton. Which is why i need the display.

Thanks for you help. It is taking me farther down the road.

dencla

@JonB It was a typo sorry. I figured it out. On to the pushbutton.

dencla

@JonB I can Drag and drop from a ui->tableView, now I need to drop to a CustomPushButton. I have promoted a ui->QPushButton to a ui->CustomPushButton. When I drag the drop indicator goes away and the drop fails. I am not sure what triggers the event.

Below is the code for the CustomPushButton::

#include <QPushButton>
#include <QMimeData>
#include <QDataStream>
#include <QDropEvent>
 
class CustomPushButton : public QPushButton {
public:
    CustomPushButton(QWidget *parent = nullptr) : QPushButton(parent) {
        setAcceptDrops(true);
    }

    // Override the virtual method to handle drop events
    void dropEvent(QDropEvent *event) override {
        const QMimeData *mimeData = event->mimeData();
        if (mimeData && mimeData->hasText()) {
            setText(mimeData->text());
            event->acceptProposedAction();
        }
    }
};

Any Ideas

SGaist

@dencla you also need to implement the dragEnterEvent and dragMoveEvent methods as they handle the dragging until you drop.

dencla

@SGaist OK I'll give that a shot.
Thanks

dencla

@SGaist This is what I have now. It still does not register the drag on the CustomPushButton.

#include <QPushButton>
#include <QMimeData>
#include <QDataStream>
#include <QDropEvent>
#include <QDebug>

class CustomPushButton : public QPushButton {
public:
    CustomPushButton(QWidget *parent = nullptr) : QPushButton(parent) {
        setAcceptDrops(true); // Enable drop events for the push button
    }

protected:
    void dragEnterEvent(QDragEnterEvent *event) override {
        if (event->mimeData()->hasFormat("application/vnd.text.list"))
            event->accept();
        else
            event->ignore();
    }

    void dragMoveEvent(QDragMoveEvent *event) override {
        if (event->mimeData()->hasFormat("application/vnd.text.list")) {
            event->setDropAction(Qt::CopyAction);
            event->accept();
        } else {
            event->ignore();
        }
    }

    void dropEvent(QDropEvent *event) override {
        const QMimeData *mimeData = event->mimeData();
        if (!mimeData->hasFormat("application/vnd.text.list")) {
            event->ignore();
            return;
        }

        QByteArray encodedData = mimeData->data("application/vnd.text.list");
        QDataStream stream(&encodedData, QIODevice::ReadOnly);

        QStringList items;
        while (!stream.atEnd()) {
            QString text;
            stream >> text;
            items.append(text);
        }

        qDebug() << "Dropped Items:" << items;

        // Perform actions based on the dropped items
        if(items.size() > 0) {
            setText(items.at(0));
            qDebug() << "inserted data";
        }
        // Call the base class implementation to handle other drop events
        QPushButton::dropEvent(event);
    }
};

SGaist

@dencla are you sure your overrides are called ?

dencla

@SGaist No I do't think they are, but I'm not sure. I will trace through the program but I don't think I will see anything. What would cause that. I am on ios apple mini.

dencla

@SGaist It definitely is not calling them.

dencla

@SGaist I recompiled the project in Linux and it works.
I don't know why it doesn't work on my apple computer.

Thanks

SGaist

@dencla which version of macOS are you using ?

dencla

@SGaist macOS Monterey 12.7.2

SGaist

@dencla I tested on Ventura with both 5.15.2 and 6.7.0 and your code is working. I just changed the mime type to handle plain text for testing and it's working as expected.