Model for custom object

Patrick Wright

Hello,

I have been searching and reading documentation in earnest to figure out how to create a model (to be used in a table view) for a list of custom objects. My general scenario is this: assuming I have an QList of objects of a custom class, I would like to create a model which will allow these objects to be displayed in a table where each row is an object and each column is a member variable.

I have already implemented rowCount(), columnCount(), data(), and headerData() and am able to get data to be displayed in the table when I initially perform setModel() on the QTableView. My model doesn't hold the actual data but only a pointer to a QList. For example, my constructor is

PortModel(QList<AbstractPortInfo *> *infos);

The problem I am having is figuring out how to update the view when I append/remove/change objects in the List. I have read that you should emit dataChanged() which I am doing as follows

emit dataChanged(index(infos->length() - 1, 0), index(infos->length() - 1, 1));
//Assuming the AbstractPortInfo object has 2 members wish to return

when I append an item, however this does nothing.

I don't want to hold the data in the model itself because I am using the array of objects elsewhere in scenarios where I don't need a whole model.

Any ideas as to how this can be accmplished?
Thanks in advance!

SGaist

Hi,

How are you adding data to your list ?
How do you propagate that information to the upper layers?

Patrick Wright

When I use the QList outside of the widget which has the QTableView (i.e. when I don't care about displaying the data), I simply use the append() method of the list. From within the widget with the view, I added an append() method as such

void append(AbstractPortInfo *info);

to the model so that I know when an update occurs to potentially tell the view to update.

mpergand

You must inform the item model of any changes you make to your own model.
It should look something like this:

void append(AbstractPortInfo *info)
{
beginInsertRows(QModelIndex(),infos->count(),infos->count());
infos->append(info);
endInsertRows();
}

Look at the protected methods of QAbstractItemModel Class for more.

VRonin

dataChanged only notifies that the data contained in an existing item changed.
You need to use the begin*()/end*() methods. unfortunately this makes:

don't want to hold the data in the model itself.

difficult because those methods are protected and you need to add public methods (even slots) that call those private methods

Patrick Wright

@mpergand

This works like a charm! I knew it couldn't be too difficult to achieve, I was just a bit confused.

Thank You!