Custom Table Model

[Christian Ehrlicher]

@EaccB said in Custom Table Model:

Then what do I use to signal to the view that the model has been updated?

dataChanged() as explained above.

[EaccB]

@Christian-Ehrlicher

Ok, I'm really confused. You said that I shouldn't use dataChanged() when removing a row. So, what should I do when an element is removed from the vector? Or are you saying that I should emit dataChanged from the class which owns the vector and connect it to a slot in the Model?

[Christian Ehrlicher]

@EaccB said in Custom Table Model:

So, what should I do when an element is removed from the vector?

You really really should read the documentation. I already gave a the link two times...: https://doc.qt.io/qt-5/model-view-programming.html#inserting-and-removing-rows

[JonB]

@EaccB
To reiterate what @Christian-Ehrlicher is telling you. The signal code in a model has to depend on whether you are updating an existing row which is already there and will remain there, versus if you inserting or deleting a row.

dataChanged() is only for same rows, with values in columns changing.

For inserting/deleting rows you must use begin/endInsert/RemoveRows() instead.

Views, for example, need to know this and react differently according as the model reports its rows are being updated or are being deleted/inserted. You can imagine the action they take will differ between these cases.

[EaccB]

@JonB

I think we got out wires crossed. By "update the vector", I meant add and remove elements, as well as editing existing items. This is why I was confused when @Christian-Ehrlicher suggested using dataChanged(), which he had previously told me not to use for removing elements.

If I add an element directly to the vector, do I still need to call insertRows() from the model?

[Christian Ehrlicher]

@EaccB said in Custom Table Model:

which he had previously told me not to use for removing elements.

where?

If I add an element directly to the vector, do I still need to call insertRows() from the model?

Yes, as clearly written in the docs.

[EaccB]

@Christian-Ehrlicher

You must not call dataChanged() when removing a row.

[Christian Ehrlicher]

@EaccB Sorry, I over read the not

This statement is correct.

[VRonin]

If you use the model-as-interface-on-existing-data

@EaccB said in Custom Table Model:

editing existing items

• The item that owns the data should emit a signal after the item is modified, the model will connect to this signal and emit dataChanged

I meant add and remove elements

• The item that owns the data should emit a signal before the item is added/removed, the model will connect to this signal and call beginInsertRows/beginRemoveRows
• The item that owns the data should emit a signal after the item is added/removed, the model will connect to this signal and call endInsertRows/endRemoveRows

[artwaw]

Unless the point of your exercise is to create a model - why don't you use built in sqlite for data storage (be it in memory or in a file) and use generic QSqlTableModel, where you don't have to worry about anything? Seems like much less work...