[Interest] Updating a model re-add everything in QML. How can i prevent that?

[Nicolás Ulrich]

Are you really using this?
qRegisterMetaType<PathModel*>("PathModel*");            (with the * in
the string)

I guess it should be
qRegisterMetaType<PathModel*>("PathModel");



On Thu, Nov 8, 2012 at 10:36 AM, Mark <markg85 at gmail.com> wrote:
> On Thu, Nov 8, 2012 at 10:34 AM, Bo Thorsen <bo at fioniasoftware.dk> wrote:
>> Den 08-11-2012 01:33, Mark skrev:
>>> Hi,
>>>
>>> I have a models in C++ (a QStringList actually). In QML i'm displaying
>>> it using a repeater. Now when i remove some items from the end of the
>>> list (which happens quite a few times) then the entire list seems to
>>> go through the QML repeater again.
>>>
>>> What i want to do is put a QStringList in a QML Repeater (works), but
>>> when i remove items from the end i would like QML to be "smart" and
>>> also remove the items from the end and leave those that haven't
>>> changed. Thus not re-inserting all the items in the repeater when not
>>> needed.
>>>
>>> Is there some option to get that?
>>
>> To do this you need a better model than a QStringList in Repeater. Take
>> a look at QStringListModel instead. But if you just call setStringList()
>> you won't see any improvement. You have to use insertRows and removeRows
>> instead.
>>
>> Bo Thorsen.
>>
>> Come by my DevDays talk in Berlin - "Designing for testability". Learn how to build and run your unit tests with the Qt application.
>>
>> Fionia Software - Qt experts for hire.
>>
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>
> Thanks a lot for that, that will probably work.
> However, i'm hitting another issue when trying to make a custom
> StringListModel (only due to setRoleNames...) This is how it looks:
>
> // pathmodel.h
> #ifndef PATHMODEL_H
> #define PATHMODEL_H
>
> #include <QStringListModel>
>
> class PathModel : public QStringListModel
> {
> public:
>     PathModel();
> };
>
> Q_DECLARE_METATYPE(PathModel*)
>
> #endif // PATHMODEL_H
>
>
> // pathmodel.cpp
> #include "pathmodel.h"
>
> PathModel::PathModel()
> {
>     QHash<int,QByteArray> roleNames;
>     roleNames.insert(Qt::DisplayRole, "modelData");
>     setRoleNames(roleNames);
> }
>
> Now if i want to register the new meta type using:
> qRegisterMetaType<PathModel*>("PathModel*");
>
> The app instantly crashes when i run it.. It must be something very
> obvious that i'm missing, but i don't see it.
>
> Any idea what i'm doing wrong?
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