feat(min-demo): add shared json request parsing helper

Author: 1mpossible-code

server/cities_endpoints.py

@@ -9,6 +9,7 @@
     validate_pagination,
     validate_range_filters,
 )
+from server.request_parsing import get_json_object_or_abort
 
 cities_ns = Namespace('cities', description='City operations')
 
@@ -128,16 +129,6 @@
 })
 
 
-def _get_json_body() -> dict:
-    payload = request.get_json(silent=True)
-    if payload is None or not isinstance(payload, dict):
-        cities_ns.abort(
-            HTTPStatus.BAD_REQUEST,
-            'Request body must be a valid JSON object',
-        )
-    return payload
-
-
 @cities_ns.route('')
 class CitiesList(Resource):
 
@@ -192,7 +183,7 @@ def post(self):
         Creates a new city with the provided data.
         Timestamps are automatically set by the server.
         """
-        city_data = _get_json_body()
+        city_data = get_json_object_or_abort(request, cities_ns.abort)
 
         state_code = city_data.get('state_code')
         country_code = city_data.get('country_code')
@@ -314,7 +305,7 @@ def put(self, state_code, city_name):
         Updates the city with the provided data.
         The updated_at timestamp is automatically set by the server.
         """
-        update_data = _get_json_body()
+        update_data = get_json_object_or_abort(request, cities_ns.abort)
 
         try:
             success = cities_data.update_city(

server/request_parsing.py

@@ -0,0 +1,19 @@
+"""Helpers for parsing and validating JSON request bodies."""
+
+from http import HTTPStatus
+from typing import Any, Callable
+
+from flask import Request
+
+AbortFunc = Callable[[HTTPStatus, str], None]
+
+
+def get_json_object_or_abort(request: Request, abort_func: AbortFunc) -> dict[str, Any]:
+    """Return a JSON object payload or abort with a consistent 400 error."""
+    payload = request.get_json(silent=True)
+    if payload is None or not isinstance(payload, dict):
+        abort_func(
+            HTTPStatus.BAD_REQUEST,
+            'Request body must be a valid JSON object',
+        )
+    return payload