log error and skip caching if serializing a dictionary with non-str keys

shared/helpers/cache.py

@@ -15,6 +15,22 @@
 DEFAULT_TTL = 120
 
 
+def attempt_json_dumps(value: Any) -> str:
+    def assert_string_keys(d: dict[Any, Any]) -> None:
+        for k, v in d.items():
+            if type(k) is not str:
+                raise TypeError(
+                    f"Attempted to JSON-serialize a dictionary with non-string key: {k}"
+                )
+            if isinstance(v, dict):
+                assert_string_keys(v)
+
+    if isinstance(value, dict):
+        assert_string_keys(value)
+
+    return json.dumps(value)
+
+
 def make_hash_sha256(o: Any) -> str:
     """Provides a machine-independent, consistent hash value for any object
 
@@ -104,12 +120,14 @@ def get(self, key: str) -> Any:
 
     def set(self, key: str, ttl: int, value: Any):
         try:
-            serialized_value = json.dumps(value)
+            serialized_value = attempt_json_dumps(value)
             self.redis_connection.setex(key, ttl, serialized_value)
         except RedisError:
             log.warning("Unable to set cache on redis", exc_info=True)
         except TypeError:
-            log.exception("Attempted to cache a type that is not JSON-serializable")
+            log.exception(
+                f"Attempted to cache a type that is not JSON-serializable: {value}"
+            )
 
 
 class LogMapping(dict):

tests/unit/helpers/test_cache.py

@@ -95,6 +95,13 @@ def test_simple_redis_call_not_json_serializable(self):
         redis_backend.set("normal_key", 120, unserializable)
         assert redis_backend.get("normal_key") == NO_VALUE
 
+    def test_simple_redis_call_dict_with_int_keys(self):
+        redis_backend = RedisBackend(FakeRedis())
+
+        d = {"abcde": {1: [1, 2, 3], 2: [4, 5, 6]}}
+        redis_backend.set("normal_key", 120, d)
+        assert redis_backend.get("normal_key") == NO_VALUE
+
 
 class TestCache(object):
     def test_simple_caching_no_backend_no_params(self, mocker):