Make sure 204 status responses have no body in accordance with HTTP spec (geopython#2094)

* Fix provider no data error

* fix flake8

* address feedback

* fix gzip issue which adds a header and deviates from the spec

Author: C-Loftus

pygeoapi/api/__init__.py

@@ -604,6 +604,10 @@ def get_exception(self, status, headers, format_, code,
         else:
             content = to_json(exception, self.pretty_print)
 
+        if status == HTTPStatus.NO_CONTENT:
+            LOGGER.error('HTTP 204 detected, suppressing content')
+            content = ''
+
         return headers, status, content
 
     def get_format_exception(self, request) -> Tuple[dict, int, str]:

pygeoapi/starlette_app.py

@@ -33,6 +33,7 @@
 """ Starlette module providing the route paths to the api"""
 
 import asyncio
+from http import HTTPStatus
 import os
 from typing import Callable, Union
 from pathlib import Path
@@ -133,9 +134,10 @@ async def execute_from_starlette(api_function, request: Request, *args,
         headers, status, content = await loop.run_in_executor(
             None, call_api_threadsafe, loop, api_function,
             actual_api, api_request, *args)
-        # NOTE: that gzip currently doesn't work in starlette
-        #       https://github.com/geopython/pygeoapi/issues/1591
-        content = apply_gzip(headers, content)
+        # 204 responses must have an empty body, but gzip
+        # encoding would add gzip metadata, thus we skip
+        if status != HTTPStatus.NO_CONTENT:
+            content = apply_gzip(headers, content)
 
     response = _to_response(headers, status, content)
 

tests/api/test_api.py

@@ -847,7 +847,10 @@ def test_get_exception(config, api_):
     assert content['code'] == 'NoApplicableCode'
     assert content['description'] == 'oops'
 
-    d = api_.get_exception(500, {}, 'html', 'NoApplicableCode', 'oops')
+    d = api_.get_exception(204, {}, 'html', 'NoApplicableCode', 'oops')
+    assert len(d[2]) == 0
+    d = api_.get_exception(204, {}, 'json', 'NoApplicableCode', 'oops')
+    assert len(d[2]) == 0
 
 
 def test_evaluate_limit():