JSON type validate decorator for Django REST framework

request_validate.py

import functools
from enum import Enum

from rest_framework.response import Response


class BadRequest(Response):
    """400 Bad Request
    May be used to indicate nonspecific failure.
    400 is the generic client-side error status, used when no other 4xx error
    code is appropriate.
    """

    status_code = 400

    
def bad_request(message: str):
    return BadRequest({"message": message})


class JSONDataType(Enum):
    """JSON data types"""

    BOOLEAN = "boolean"
    NUMBER = "number"
    STRING = "string"
    OBJECT = "object"
    ARRAY = "array"
    NULL = "null"

    def check_type(self, value):
        mapping = {
            self.BOOLEAN: bool,
            self.NUMBER: (int, float),
            self.STRING: str,
            self.OBJECT: dict,
            self.ARRAY: list,
            self.NULL: None,
        }
        return isinstance(value, mapping[self])


# fmt: off
def request_validate(json_type: JSONDataType):
    def validate_decorator(func):
        @functools.wraps(func)
        def wrapper(*args, **kwargs):
            if not json_type.check_type(args[1].data):
                return bad_request(f"Body should be a JSON {json_type.value}")
            return func(*args, **kwargs)
        return wrapper
    return validate_decorator
# fmt: on


# Use it like this
@action(methods=["PUT"], detail=False)
@request_validate(json_type=JSONDataType.OBJECT)
def dog(self, request):
    pass