Merge pull request #934 from akrherz/no_mckey

Allow bypass of memcache check in iemapp()

.pre-commit-config.yaml

@@ -2,7 +2,7 @@ ci:
   autoupdate_schedule: quarterly
 repos:
   - repo: https://github.com/astral-sh/ruff-pre-commit
-    rev: "v0.5.1"
+    rev: "v0.5.2"
     hooks:
       - id: ruff
         args: [--fix, --exit-non-zero-on-fix]

CHANGELOG.md

@@ -14,6 +14,8 @@ All notable changes to this library are documented in this file.
 
 - Add `_check_dueling_tropics` VTEC check looking for TR+HU overlap (#930).
 - Cross check WCNs against watch database storage for PDS status (#925).
+- For `iemapp` if the `memcachekey=` callable returns `None`, the check of
+memcache is short circuited.
 
 ### Bug Fixes
 

src/pyiem/webutil.py

@@ -354,6 +354,9 @@ def _mcall(func, environ, start_response, memcachekey, expire, content_type):
     if memcachekey is None:
         return func(environ, start_response)
     key = memcachekey if isinstance(memcachekey, str) else memcachekey(environ)
+    if key is None:
+        # An appside short circuit when we programatically do not want cache
+        return func(environ, start_response)
     mc = Client("iem-memcached:11211")
     res = mc.get(key)
     if not res:
@@ -392,7 +395,7 @@ def iemapp(**kwargs):
           single cursor name with `iemdb_cursorname=<name>`.
         - schema (BaseModel): A Pydantic model to parse the form with.
         - memcachekey (str or callable): A memcache key to use for caching
-          the response.
+          the response. If the callable returns `None`, no caching is done.
         - memcacheexpire (int): The number of seconds to cache the response.
         - content_type (str or callable): The content type to use for the
           response.

tests/test_webutil.py

@@ -26,6 +26,23 @@
 )
 
 
+def test_memcachekey_is_none():
+    """Test that we can handle a None memcachekey."""
+
+    @iemapp(memcachekey=lambda _e: None)
+    def application(_environ, _start_response):
+        """Test."""
+        return f"aa{random.random()}".encode("ascii")
+
+    env = {
+        "wsgi.input": mock.MagicMock(),
+        "QUERY_STRING": "",
+    }
+    sr = mock.MagicMock()
+    res1 = application(env, sr)[0]
+    assert res1.startswith(b"aa")
+
+
 def test_iemapp_memcache_keychanged():
     """Test the memcache option."""