Python/Flask: Return Message and Status Code to calling function?

Question

I have a Flask App (build on top of the Flask Restx Resource class) and I've created a couple of try/except statements to validate the input of my app.

To make the code of the app more readable, I'd like to encapsulate these checks in a seperate function. But this introduces the challenge of returning the error message and Status Code correctly so that it can be handled by the API.

Is there a way to make the function return via the calling function or so?

# minimal example
from flask import Flask
from flask_restx import Api, Resource

app = Flask(__name__)
api = Api(app)

def validate_input(a):
    try:
        assert a < 10
    except:
        return "a >= 10", 500

@api.route("/<a>")
class BatchScorer(Resource):
    def get(self, a):

        # validate_input(a):

        # instead of?

        try:
            assert a < 10
        except:
            return "a >= 10", 500


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

Matteo Pasini · Accepted Answer · 2021-07-20 13:38:27Z

1

Add a return value to the checking function, and simply return the value returned by that function

from flask import Flask, Response
from flask_restx import Api, Resource

app = Flask(__name__)
api = Api(app)

def validate_input(a):        
    if (a < 10):
        return Response(response="a < 10", status=200)
    else:
        return Response(response="a >= 10", status=500)

@api.route("/<a>")
class BatchScorer(Resource):
    def get(self, a):
        return validate_input(a)


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

edited Jul 20, 2021 at 13:38

answered Jul 20, 2021 at 13:25

Matteo Pasini

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2 Comments

stats-hb Over a year ago

what will be returned by return validate_input(a) if a is < 10? Then validate_input(a) will not return anything and therefore the "outer" return will not end the function?

Matteo Pasini Over a year ago

Obviously it needs to be handled, add another return Response (response = "a <10", status = 200), if that's how you want to handle it, I just reused your code, I don't know what you need to do specifically

charchit · Accepted Answer · 2021-07-20 13:24:29Z

1

As you are returning two things in the function. So you can just call function and return it which will return.

[...]
return validate_input(a)

answered Jul 20, 2021 at 13:24

charchit

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