Hi everyone,
While trying to submit a patch to fix QStringListModel::setItemData
https://codereview.qt-project.org/235730 we opened a much larger discussion on
QAbstractItemModel, that expanded on the forum
https://forum.qt.io/topic/93207/qabstractitemmodel-setitemdata-partial-success
but that I ultimately would like your opinion on:
At the moment, QAbstractItemModel::setItemData calls setData for each role
until the first failure and returns false if that happens.
This opens up 2 issues:
* QAbstractItemModel::setItemData returns false even when some but not
all data was actually set without rolling back the changes
* QAbstractItemModel::setItemData depends on the ordering of the roles
For the second point, an example that illustrates the problem is
(QStringListModel::setItemData just uses the base class implementation):
QStringListModel::setItemData({{Qt::DisplayRole,QVariant("test")},{
Qt::DecorationRole,QVariant(QIcon())}) will return false but actually set the
string to "test"
QStringListModel::setItemData({{Qt::EditRole,QVariant("test")},{
Qt::DecorationRole,QVariant(QIcon())}) will return false and do nothing on the
model
My proposal is:
* Remove the ordering-dependency QAbstractItemModel::setItemData (i.e.
sets all the roles it can and returns false if any of them failed)
* Make setItemData in subclasses of QAbstractItemModel behave
transaction-like (i.e. try to set all the roles, if any fails rollback the
other changes and return false)
This however is technically a change of behaviour so I would like people way
smarter than me to agree on the way forward.
Thanks,
Regards,
Luca Beldi (aka VRonin)
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