parsing_lib: fix error on get() call for non-dictionaries

.get("location", {}).get("country") raises AttributeError
when {"location": None} as None is not a dictionary.

Add deep_get() from export-data/transform.py to common_lib
for access to keys within nested dictionaries.

ingestion/functions/common/common_lib.py

@@ -16,6 +16,9 @@
 import functools
 from enum import Enum
 from pathlib import Path
+from typing import Any
+from functools import reduce
+from typing import Dict
 
 import google
 import google.auth.transport.requests
@@ -179,6 +182,17 @@ def python_module(folder: Path, root: Path):
         return None
 
 
+def deep_get(dictionary: Dict[str, Any], keys: str, default=None) -> Any:
+    """
+    Retrieve values from nested dictionaries
+    """
+    return reduce(
+        lambda d, key: d.get(key, default) if isinstance(d, dict) else default,
+        keys.split("."),
+        dictionary,
+    )
+
+
 def get_parser_module(parser):
     parser_name = re.sub(r"-ingestor-\w+", r"", parser)
     parser_name = re.sub(r"-", r".", parser_name)

ingestion/functions/common/parsing_lib.py

@@ -191,12 +191,11 @@ def prepare_cases(cases: Generator[Dict, None, None], upload_id: str, excluded_c
     """
     for case in cases:
         case["caseReference"]["uploadIds"] = [upload_id]
-        if country := case.get("location", {}).get("country"):
+        if country := common_lib.deep_get(case, "location.country"):
             case["location"]["country"] = iso3166_country_code(country)
-        if case.get("travelHistory") and case.get("travelHistory").get("travel"):
-            for travel in case["travelHistory"]["travel"]:
-                if travel_country := travel.get("location", {}).get("country"):
-                    travel["location"]["country"] = iso3166_country_code(travel_country)
+        for travel in common_lib.deep_get(case, "travelHistory.travel", default=[]):
+            if travel_country := common_lib.deep_get(travel, "location.country"):
+                travel["location"]["country"] = iso3166_country_code(travel_country)
         if (excluded_case_ids is None) or ("sourceEntryId" not in case["caseReference"]) or (not case["caseReference"]["sourceEntryId"] in excluded_case_ids):
             yield remove_nested_none_and_empty(case)