[REQ] Support Set in python for array w/ uniqueItems=True

[Gidgidonihah]

Is your feature request related to a problem? Please describe.

In upgrading from 5.0.1 to 5.1.0 I found that the types changed for arrays with uniqueItems=True from Set to list. For us, this was a breaking change as we rely upon type hints.

Describe the solution you'd like

IMO, Set should be mapped to set in python, rather than to list. The tradeoff is that the array is not ordered, but it enforces (or rather easily allows us to enforce when deserializing using the supplied type) the uniqueItems constraint.

Describe alternatives you've considered

Alternatively, we don't marshall with set, and alter to the templates to handle duplicate values with uniqueItems.

Additional context

The refactor to add a python ABC in essence added a Set to list mapping to the AbstractPythonConnexionServerCodegen class via AbstractPythonCodegen, whereas previously it assumed a model of Set. This worked well as we could from typing import Set.

We then had custom templates that looked at __origin__ and applied mutations. As of 5.1 Set is now mapped to list and no longer allows us to do so.

Additionally, when using the python-flask templates, Set is currently mapped to list whereas array is currently mapped to List.

See also #8784

[wing328]

Thanks for reporting the issue. I'll see what I can do to fix it this week.

[spacether]

uniqueItems has been added to the python-experimental generator in #8325
The data type was kept as tuple to allow other schemas with type list->(enforced as tuple) lacking uniqueItems to correctly validate against a list payload with unique items.
That way data like
[0, 1]
will validate against: ListWithUniqueItems + ListWithMinItems + SomeComposedSchema

ListWithUniqueItems:
  type: array
  uniqueItems: true
ListWithMinItems:
  type: array
  minItems: 2
SomeComposedSchema:
  allOf:
  - ListWithUniqueItems
  - ListWithMinItems

[spacether]

Closing this issue because uniqueItems is implement in python-experimental