Improve protection against old unsupported objects (e.g. LocationSourceForCallsign.NONE) coming back from the cache and throwing exceptions

core/sig_lookup_helper.py

@@ -114,16 +114,23 @@ def get_sig_ref_info(sig_name, ref_id):
         # OK, this is something we have to look up. Now check to see if our data store contains reference data and if
         # so, copy the data into the sig_ref object
         key = f"{sig_name}:{ref_id}"
-        lookup_data = DATA_STORE.sigrefs.get(key) if key in DATA_STORE.sigrefs else None
-        if lookup_data:
-            for key, value in lookup_data.__dict__.items():
-                if value is not None and sig_ref.__dict__.get(key) is None:
-                    sig_ref.__dict__[key] = value
+        try:
+            lookup_data = DATA_STORE.sigrefs.get(key) if key in DATA_STORE.sigrefs else None
+            if lookup_data:
+                for key, value in lookup_data.__dict__.items():
+                    if value is not None and sig_ref.__dict__.get(key) is None:
+                        sig_ref.__dict__[key] = value
 
-        else:
-            # Maybe a super new reference we don't know about yet, but more likely a typo or a test reference,
-            # just silently ignore it.
-            logger.debug(f"{sig_name} database did not contain data for ref {ref_id}")
+            else:
+                # Maybe a super new reference we don't know about yet, but more likely a typo or a test reference,
+                # just silently ignore it.
+                logger.debug(f"{sig_name} database did not contain data for ref {ref_id}")
+
+        except (ValueError, KeyError):
+            # Catch exceptions due to e.g. old versions of objects in the cache that are no longer compatible,
+            # and remove them from the cache.
+            del DATA_STORE.sigrefs[key]
+            return None
 
     except Exception:
         logger.exception(f"Exception when looking up sig_ref info for {sig_name} ref {ref_id}")