On 25/08/2020 05.58, Giuseppe D'Angelo via Development wrote:
Il 25/08/20 07:49, Thiago Macieira ha scritto:
But how about models? This is an honest question. Does it make sense for
tables and lists that big? Note that an item*view* has a purpose of
being viewed, so how does one display such a huge list, tree or
table?
Just another thought -- models may not necessarily used directly with
views but as data sources for other business logic parts of the
application (including but not necessarily limited to proxy models).
Given the underlying data sources are 64-bit capable, such models should
be as well.
Indeed; this is sort of the approach one of my applications takes.
Although we do usually end up with a view on top of the model (often
after a few levels of indirection¹), we also use models (i.e.
QAbstractItemModel) to drive things like graphical displays. (It would
take some words to explain our actual use case, but think of using a
model as the source for a scatter plot and you sort-of get the idea.)
That said, I suspect you would run into fairly severe performance
problems trying to use a model with more than 2^31 rows...
(¹ We generally have one model that presents the data in an abstract
fashion, using data roles rather than columns as field identifiers. This
separates what the data *is* from how it's presented. This may get fed
into one or more sort/filter proxy models before being fed into a
"representation" model, which folds, spindles and mutilates the
fields-as-data-roles model into a fields-as-columns model suitable for
being fed into e.g. QTreeView. One nice feature is that the
representation can accept a list of what fields you want to have in the
view.)
--
Matthew
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