swag_from with "schema": MyMarshmallowSchema always generates Swagger 2.0 style references

[kiranzo]

So, I have a Flask project where I want to generate Swagger docs with Flasgger, Apispec and Marshmallow.

Since I want to use requestBody, I moved to OpenAPI 3.0.2, and when I did it, Swagger showed me errors saying that it can't find my schemas, because the definitions themselves moved under components/schemas/MyMarshmallow (without the "Schema" part), but for endpoints, schemas are still in "$ref": "#/definitions/MyMarshmallowSchema".

The code that leads to this:

from flask import Flask
from apispec.ext.marshmallow import MarshmallowPlugin
from apispec_webframeworks.flask import FlaskPlugin
from flasgger import APISpec, Swagger
from app.my_api import api_blueprint

spec = APISpec(
    title="My Test API",
    version="1.0.0",
    openapi_version="3.0.2",
    info=dict(description="My Test API"),
    plugins=[
        FlaskPlugin(),
        MarshmallowPlugin(),
    ],
)

flask_app = Flask(__name__)
# just in case
flask_app.config['SWAGGER'] = {
    'uiversion': 3,
    'title': 'My Test API',
    'openapi': '3.0.2'
}

template = spec.to_flasgger(
    flask_app,
    definitions=[MyMarshmallowSchema]
 )
swag = Swagger(flask_app, template=template)

flask_app.register_blueprint(api_blueprint)

flask_app.run(debug=True)

and swag_from for my endpoint:

from schemas import MyMarshmallowSchema
from flasgger import swag_from
api_blueprint = Blueprint("my_blueprint", __name__, url_prefix="/api")

@api_blueprint.route("/my-route", methods=["GET"])
@swag_from({
    "tags": ["mytag"],
    "responses": {
        HTTPStatus.OK.value: {
            "description": "test",
            "schema": MyMarshmallowSchema
        },
    }
})
def test():
........

Basically, this results in a broken swagger, because the schema definition is de facto under components/schemas/MyMarshmallow (OpenAPI 3.0.2 style) , but methods expect it to be under "$ref": "#/definitions/MyMarshmallowSchema" (Swagger 2.0 style).

Since this came from the swag_from, I think it's Flasgger's fault, and I already told it I'm using OpenAPI 3.0.2 in APISpec object and in Flask 'SWAGGER' config part.

I solved this by manually changing the definition to "schema": {"$ref": "#/components/schemas/MyMarshmallow" } in swag_from, but I don't think this is the correct behaviour.