Most applications will have data that needs to be displayed to the user. That data might come from a variety of sources: network sources, local files, and databases are all common sources of data.
It is often advantageous to show similar data in a similar manner, within an application, and this gives rise to the idea of having a model which contains data, and a view which displays the data. The view will display a delegate for every datum in the model.
For information about how the Model/View paradigm is implemented in Qt Quick, see the page titled Models and Views in Qt Quick.
Databases are commonly used to store information in applications. Qt Quick provides simplified access to relational databases via the QtQuick.LocalStorage module.
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