add support for argparse's dest

rest_tools/server/arghandler.py

@@ -10,7 +10,7 @@
 import sys
 import time
 import traceback
-from typing import Any, List, TypeVar, Union
+from typing import Any, List, TypeVar, Union, cast
 
 import tornado.web
 from tornado.escape import to_unicode
@@ -76,12 +76,13 @@ def retrieve_json_body_arg(parsed_val: Any) -> Any:
             if parsed_val != USE_CACHED_VALUE_PLACEHOLDER:
                 return parsed_val  # this must be the **default** value
             # replace placeholder value with actual value
+            key = cast(str, name or kwargs.get("dest"))
             try:
-                return self.rest_handler.json_body_arguments[name]
+                return self.rest_handler.json_body_arguments[key]
             except KeyError as e:
                 # just in case, intercept so the user doesn't get a 400
                 raise RuntimeError(
-                    f"key '{name}' should exist in json body arguments"
+                    f"key '{key}' should exist in json body arguments"
                 ) from e
 
         # TYPE

tests/unit_server/arghandler_test.py

@@ -388,3 +388,44 @@ def test_141__extra_argument_with_duplicates(argument_source: str) -> None:
         with pytest.raises(tornado.web.HTTPError) as e:
             arghand.parse_args()
         assert str(e.value) == "HTTP 400: unrecognized arguments: xtra, another"
+
+
+@pytest.mark.parametrize(
+    "argument_source",
+    [QUERY_ARGUMENTS, JSON_BODY_ARGUMENTS],
+)
+def test_200__argparse_dest(argument_source: str) -> None:
+    """Test `argument_source` arguments using argparse's advanced options."""
+    args: Dict[str, Any] = {
+        "old_name": "-10",
+        "bar": "True",
+    }
+    if argument_source == JSON_BODY_ARGUMENTS:
+        args.update(
+            {
+                "dicto": {"abc": 123},
+                "listo": [1, 2, 3],
+            }
+        )
+
+    # set up ArgumentHandler
+    arghand = setup_argument_handler(argument_source, args)
+
+    for arg, _ in args.items():
+        print()
+        print(arg)
+        if arg == "old_name":
+            arghand.add_argument("new_name")
+        else:
+            arghand.add_argument(arg)
+    outargs = arghand.parse_args()
+
+    # grab each
+    for arg, val in args.items():
+        print()
+        print(arg)
+        print(val)
+        if arg == "old_name":
+            assert val == getattr(outargs, "new_name")
+        else:
+            assert val == getattr(outargs, arg.replace("-", "_"))