QModelIndex value for the root of a tree model

[anda_skoa]

I’ve attempted to make a QModelIndex at row 0 column 0 but since there is no parent for that position, it doesn’t quite work. I have also used a null QModelIndex using QModelIndex() as the parent, and that too, does not appear to work.

The null/empty QModelndex represents the root of a tree model

QVariant rootDisplayRoleData = model->data(QModelIndex(), Qt::DisplayRole);

QVariant rootDisplayRoleData = model->data(QModelIndex(), Qt::DisplayRole);

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Toplevel nodes therefore have that as their parent

QModelIndex topLevelRow0Column0 = model->index(0, 0, QModelIndex());
QVariant displayRoleDataRow0Column0 = model->data(topLevelRow0Column0, Qt::DisplayRole);

QModelIndex topLevelRow0Column0 = model->index(0, 0, QModelIndex());
QVariant displayRoleDataRow0Column0 = model->data(topLevelRow0Column0, Qt::DisplayRole);

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Of course accessing the model's index API directly is rarely necessary, signals carry QModelIndex arguments and delegates also get told which index they are to work on.

Cheers,
_