Sort QComboBox mapped to SqlRelationalTableModel with QDataWidgetMapper

I'm using the standard pattern to decorate a comboBox's list items with the values from a mapped column (mapping foreign key -> text column), but I cannot find a pattern that also allows one to use the QSortFilterProxyModel class to sort the secondary (mapped) column values (text, ascending order) in the comboBox.

Given a table like:

Code:

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1	unassigned
2	assigned
3	active
4	suspended
5	failed
6	finished

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I want the mapped comboBox to display:

Code:

---

active
assigned
failed
finished
suspended
unassigned

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