On Wednesday 20 August 2014 20:49:03 Marc Mutz wrote:
> I don't find the QVariant::isNull behaviour any useful or intuitive. It's
> too smart. You can always use v.value<T>().isNull() because value() will
> return a default-constructed T if invalid.
I agree it's not intuitive, but it's there and this feature is used by QtSql.
When getting a nullable column, a null entry is signalled by a typed QVariant
for which isNull() == true.
I'd have preferred that QtSql use optionals to indicate such columns:
varchar => QOptional<QString>
varchar not null => QString
The question I have is: how can we prepare a transition from current state
(both a QString) in such a way that doesn't break existing code?
Should it be a connection-time option for QSqlDatabase? Maybe a query-time
option?
The goal should be to add this feature in Qt 5 and convince people to switch
to the new behaviour, so we might be able to deprecate the nullable QVariant
in Qt 5 and remove by Qt 6.
--
Thiago Macieira - thiago.macieira (AT) intel.com
Software Architect - Intel Open Source Technology Center
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