None is not of type 'number'

[miaokela]

When I use float type in model, the field value carried in the send request is None, model validation is fine, but what is this document validation? Why can't you pass?

[peter-doggart]

Can you provide a minimal example of this issue? I can pass a float to a model fine:

from flask import Flask, Blueprint, request
from flask_restx import Api, Resource, fields

api_v1 = Blueprint("api", __name__, url_prefix="/api/1")

api = Api(
    api_v1,
    version="1.0",
    title="Todo API",
    description="A simple TODO API",
)

ns = api.namespace("todos", description="TODO operations")

todo = api.model(
    "Todo", {"threshold": fields.Float(required=True, description="A float value")}
)

parser = api.parser()
parser.add_argument(
    "threshold", type=float, required=True, help="A float value", location="json"
)

@ns.route("/threshold")
class Test(Resource):
    """Put a single item with float"""
    @api.expect(todo, validate=True)
    def post(self):
        """Update a given resource"""
        args = parser.parse_args()

        print(f"You can access the float via the parser: {args['threshold']}")
        print(f"Or you can access it from the request: {request.json['threshold']}")

        return "Ok", 200

if __name__ == "__main__":
    app = Flask(__name__)
    app.register_blueprint(api_v1)
    app.run(debug=True)

Running:

curl -X 'POST' \
  'http://127.0.0.1:5001/api/1/todos/threshold' \
  -H 'accept: application/json' \
  -H 'Content-Type: application/json' \
  -d '{
  "threshold": 475.12
}'

Prints:

You can access the float via the parser: 475.12
Or you can access it from the request: 475.12

[miaokela]

Take your example, Float type has no way to submit the None value, what can be adjusted to allow this null value, 0 May be syntactically null for Float, but 0 May make sense for practical situations, such as the temperature will be lower than 0, I use 0 as a threshold, not no temperature

[peter-doggart]

As you say, this is correct because None is not a valid Float value and JSON doesn't have a nice way to pass NaN which would be a valid float.

My suggestion would be, since passing null is effectively the same as not passing a value, make the field optional then infer in code if the user set it or not with something like:

request.json.get('threshold', np.nan)

[miaokela]

Perhaps rewrite the double underscore method is not reasonable, in view of the scenario requirements, or rewrite flask_restx.Resource.__validate_payload, there will be None value of the data is not checked, so as to solve the current problem, thank you for your help