disable a parent and children in a tree model

[qt_gotcha]

working with editable tree model in the examples
I want to disable certain branches when the user selects certain options in the interface.

Should this be done by setting the flags of the parent of a branch to disable, using Qt::ItemIsEnabled?

How can I do that?
thanks

[wysota]

Yes, you have to return proper flags from your flags() implementation.

[qt_gotcha]

sorry, I am not being clear. There is no implementation example of "setflags()" or something. The implemebntation of flags in the editabletreemodel example is

Qt::ItemFlags TreeModel::flags(const QModelIndex &index) const
{
[...]
}
I don't understand when this is called. It seems to be done automatically when the treemodel is viewed? How can I set a flag of an item at a given index?
thanks

[wysota]

You don't set a flag, you return flags whenever someone asks for them. When the model tells the environment that a particular index has changed its data, all the views will probably re-ask for the flags so at this point you may return something different than before.

Qt::ItemFlags MyModel::flags(...) const {
  Qt::ItemFlags defFlags = BaseClass::flags(index);
  if(shouldBeDisabled(index))
    defFlags &= ~Qt::ItemIsEnabled;
  return defFlags;
};

Qt::ItemFlags MyModel::flags(...) const {
  Qt::ItemFlags defFlags = BaseClass::flags(index);
  if(shouldBeDisabled(index))
    defFlags &= ~Qt::ItemIsEnabled;
  return defFlags;
};

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[qt_gotcha]

thanks, that got me further. Disabling a parent does not disable the children. After some trying my solution is as follows: when a certain branch has to be disabled I take the row of the parent of that branch, and in flags the only line to be added is:
if (index.row() == rowdisable|| index.parent().row() == rowdisable)
flags &= ~Qt::ItemIsEnabled;

rowdisable is an integer and member of the treemodel