[Feature Request][OpenApi3] Add support for enums

[BilliAlpha]

I am migrating my project from openapi2 and I found out that the choices parameters has disappeared in favor of enum. However it seems that this parameter is not supported in sanic-openapi.

I suppose the implementation wouldn't be more complex than adding an enum field on the Schema object.

The enum field should be supported as specified in the specifications:

The following properties are taken directly from the JSON Schema definition and follow the same specifications:
[...]
• enum

The JSON Schema definition of the enum field is:

The value of this keyword MUST be an array. This array SHOULD have
at least one element. Elements in the array SHOULD be unique.

Elements in the array MAY be of any type, including null.

An instance validates successfully against this keyword if its value
is equal to one of the elements in this keyword's array value.

https://datatracker.ietf.org/doc/html/draft-wright-json-schema-validation-00#section-5.20

[ahopkins]

@BilliAlpha Thanks. Would you be interested in taking a crack at a PR?

[BilliAlpha]

Sorry for the delay in responding, but i'll take a look at it and try something.

[artcg]

@BilliAlpha I havent tried using the new parameter structures yet, was planning on looking at it later today, but I find that adding the line enum: List[str] to L35 of openapi3/types.py allows me to do this

>>> from sanic_openapi.openapi3.types import Schema
>>> Schema(enum=["a"]).serialize()
{'enum': ['a']}

No idea if that solves your problem or not, feel free to try it out ...

[ahopkins]

@artcg That would probably be a barebones usage.

But, it probably should be:

enum: Union[List[str], Enum]

In which case we would need some logic on serialization to extract key/values from an enum.

from enum import Enum

class Color(Enum):
    RED = "red"
    GREEN = "green"
    BLUE = "blue"

print([item.value for item in Color.__members__.values()])
# ['red', 'green', 'blue']

[BilliAlpha]

@ahopkins I just saw your comment, I'll adapt the PR to support python Enums too.

[BilliAlpha]

The PR #235 was merged