question 194 CSV JSON & JSONL · medium

Validate a service's JSON settings

A service refuses to start when its settings file is wrong, but the crash message is unhelpful. Write a validator that lists every problem in plain words before the service tries to start.

Functionconfig_errors(text)

Invalid JSONreturn only ["invalid JSON at line <lineno>: <msg>"], using the JSONDecodeError's lineno and msg

Not an objectreturn only ["settings must be a JSON object"]

namerequired; must be a non-empty string, else "name must be a non-empty string"

portrequired; must be a whole number from 1 to 65535 (not true, not 8080.0, not "8080"), else "port must be a whole number from 1 to 65535"

debugoptional; if present must be true or false, else "debug must be true or false"

Returnsthe problems in the order name, port, debug; [] when the settings are valid

Examples

callconfig_errors('{"name": "orders-api", "port": 8080, "debug": false}')returns[]

callconfig_errors('{"name": "", "port": 70000}')returns['name must be a non-empty string', 'port must be a whole number from 1 to 65535']

callconfig_errors('{"name": "orders-api", "port": 8080,}')returns['invalid JSON at line 1: Illegal trailing comma before end of object']