Notify QTableView to update data

Pavel Romankov

Hello.
I have data source with its own interface. It hase methods like add(QString &name), remove(QString &name) and others.
Also I have model which is inherited from QAbstractTableModel, it implements all required methods. Model connects to data source and receive data via its interface.
And I have QTableView which is connected to my model.
After I add item with add() method to data source, what is the right way to notify model that data was changed and update TableView?

JonB

@Pavel-Romankov said in Notify QTableView to update data:

Also I have model which is inherited from QAbstractTableModel, it implements all required methods.
After I add item with add() method to data source, what is the right way to notify model that data was changed and update TableView?

Have you read https://doc.qt.io/qt-6/qabstracttablemodel.html#subclassing, which tells you what you need to implement in your subclass? For example, add()ing will invoke insertRows(). When your implementation correctly calls begin/endInsertRows() any attached views will update correctly; if you fail to implement this correctly they will not.

Pavel Romankov

@JonB

void beginInsertRows(const QModelIndex &parent, int first, int last);

requires first and last parameters. But in my case I dont know them. When I add item to data source by

dataSource.add("new item")

it doesnt return number of row.

JonB

@Pavel-Romankov said in Notify QTableView to update data:

But in my case I dont know them

You must know them, since it is your own model! You know where you add the row(s), you need to issue the correct corresponding call.

Pavel Romankov

@JonB
So i need:

add new item with

dataSorce.add("item");

get row number of new item.
notify model about this. In dataSource

emit rowInserted(int rowNumber);

in model call

beginInsertRows(QModelIndex(), rowNumber, rowNumber + 1);
endInsertRows();

right?

JonB

@Pavel-Romankov
You should put your adding into your model call (dataSorce.add("item")?) between the begin/endInsertRows().

I believe for inserting one row your call should be

beginInsertRows(QModelIndex(), rowNumber, rowNumber);

not rowNumber + 1 for last, that should be the row number it will end up as:

first and last are the row numbers that the new rows will have after they have been inserted.

I am drawing a mental blank on emit rowInserted(int rowNumber);, I don't think you do anything for that, doesn't QAbstractTableModel do that for you from endInsertRows()? TBH I'm not sure, see https://forum.qt.io/topic/66484/how-to-update-qtableview-when-rows-are-inserted-to-it. Maybe see whether that signal gets emitted for you or whether you have to do it....