Add a note about supported OpenAPI versions

[filippog]

Describe the bug
The configuration I'm generating a client for declares parameters with in: body, the generation fails with openapi-python-client version: 0.5.4 however:

ERROR parsing POST /alerts within alert. Endpoint will not be generated.
Parameter must be declared in path or query
Parameter(name='alerts', param_in='body', description='The alerts to create', required=True, deprecated=False, allowEmptyValue=False, style=None, explode=False, allowReserved=False, param_schema=Reference(ref='#/definitions/postableAlerts'), example=None, examples=None, content=None)

To Reproduce
Steps to reproduce the behavior:
openapi-python-client generate --url https://raw.githubusercontent.com/prometheus/alertmanager/master/api/v2/openapi.yaml

I'm not familiar with OpenAPI specs and versions, e.g. if this is relevant? https://swagger.io/docs/specification/2-0/describing-request-body/

[dtkav]

Hey @filippog - consider upgrading your spec from openapi 2.0 to openapi 3.0 using a tool like this: https://mermade.org.uk/openapi-converter
It seems this tool is mostly focused on openapi 3.0 support.

[dbanty]

Thanks for answering this @dtkav! You're 100% correct in that this tool only supports OpenAPI 3. I should probably add a note about that to the README and maybe even check for the top level swagger key and emit an early error.

[filippog]

Thank you very much folks for the answers! I agree being more explicit on which openapi/swagger versions are supported will be of great help to users

[dbanty]

All set, a message is now available in the README.