Model / View - Design Question

[antarctic]

I did an implementation with two proxies, but it was really ugly.
- I had to analyse the content of the nodes for the differnt views (specially requirement).
- You can't create an index for the source model (you must store it, which results in a lot of duplicated QModelIndexes, or you have to implement a workaround, to be able to set the model pointer correct in the index). for a huge amout of data not really nice.
- The nodes knows the header and with proxies you have to set the headers far away from the nodes.

Returning a lot of different columns in one model (all available columns for all nodes) and then filtering out what's necessary is painful.

suppose (a concrete example - the real application is much more painful):

room
..+device
....+-chip
......+-pin

where the headers are
room: floor, size, costs, ............
device: supplier, pin-count, supply-voltage, .......
pin: mode, trigger-voltage, period, ...........
...
...
...

it's different from file browser or something else, where you show more or less the
same data for each node. one model with one header.

best regards,
bernd

[wysota]

Aren't you overcomplicating things? Try to break your functionality into fundamental properties and then start thinking about the architecture of the model. If you have to store indexes instead of calculating them then it means your design is wrong.

[antarctic]

How to calulate the source model index from the proxy model index (the other direction is no problem). Especially for a tree model ? Seems this problem have other people too :

http://api.kde.org/4.2-api/kdepim-ap...pp-source.html

00055 namespace {
00056 // Think this is ugly? Well, it's not from me, it comes from QProxyModel
00057 struct KDPrivateModelIndex {
00058 int r, c;
00059 void *p;
00060 const QAbstractItemModel *m;
00061 };
00062 }

And make a static_cast :-(
(There is another link, where it's better documented).

I can't think about restructuring the domain model. This is legacy code and it must not be changed (software requirement). (by the way, I think it isn't changeable anyway. 15 years growing code - with a really huge database behind. And no one has money today. It's a shame :-)

I would appreciate to know a good source about proxies using Q...Model, or when you can post something.

best regards,
Bernd

Nevertheless: QT is the best GUI framework I've ever seen.

[wysota]

If someone bases his code on deprecated QProxyModel then I have no comments on that

As for your situation - I mean the design of the internals of the model, not what it represents.