Add an option to `HfArgumentParser.parse_{dict,json_file}` to raise an Exception when there extra keys (#18692)

* Update parser to track unneeded keys, off by default

* Fix formatting

* Fix docstrings and defaults in HfArgparser

* Fix formatting

src/transformers/hf_argparser.py

@@ -234,29 +234,60 @@ class HfArgumentParser(ArgumentParser):
 
             return (*outputs,)
 
-    def parse_json_file(self, json_file: str) -> Tuple[DataClass, ...]:
+    def parse_json_file(self, json_file: str, allow_extra_keys: bool = False) -> Tuple[DataClass, ...]:
         """
         Alternative helper method that does not use `argparse` at all, instead loading a json file and populating the
         dataclass types.
+
+        Args:
+            json_file (`str` or `os.PathLike`):
+                File name of the json file to parse
+            allow_extra_keys (`bool`, *optional*, defaults to `False`):
+                Defaults to False. If False, will raise an exception if the json file contains keys that are not
+                parsed.
+
+        Returns:
+            Tuple consisting of:
+
+                - the dataclass instances in the same order as they were passed to the initializer.
         """
         data = json.loads(Path(json_file).read_text())
+        unused_keys = set(data.keys())
         outputs = []
         for dtype in self.dataclass_types:
             keys = {f.name for f in dataclasses.fields(dtype) if f.init}
             inputs = {k: v for k, v in data.items() if k in keys}
+            unused_keys.difference_update(inputs.keys())
             obj = dtype(**inputs)
             outputs.append(obj)
-        return (*outputs,)
+        if not allow_extra_keys and unused_keys:
+            raise ValueError(f"Some keys are not used by the HfArgumentParser: {sorted(unused_keys)}")
+        return tuple(outputs)
 
-    def parse_dict(self, args: dict) -> Tuple[DataClass, ...]:
+    def parse_dict(self, args: Dict[str, Any], allow_extra_keys: bool = False) -> Tuple[DataClass, ...]:
         """
         Alternative helper method that does not use `argparse` at all, instead uses a dict and populating the dataclass
         types.
+
+        Args:
+            args (`dict`):
+                dict containing config values
+            allow_extra_keys (`bool`, *optional*, defaults to `False`):
+                Defaults to False. If False, will raise an exception if the dict contains keys that are not parsed.
+
+        Returns:
+            Tuple consisting of:
+
+                - the dataclass instances in the same order as they were passed to the initializer.
         """
+        unused_keys = set(args.keys())
         outputs = []
         for dtype in self.dataclass_types:
             keys = {f.name for f in dataclasses.fields(dtype) if f.init}
             inputs = {k: v for k, v in args.items() if k in keys}
+            unused_keys.difference_update(inputs.keys())
             obj = dtype(**inputs)
             outputs.append(obj)
-        return (*outputs,)
+        if not allow_extra_keys and unused_keys:
+            raise ValueError(f"Some keys are not used by the HfArgumentParser: {sorted(unused_keys)}")
+        return tuple(outputs)

tests/utils/test_hf_argparser.py

@@ -245,6 +245,19 @@ class HfArgumentParserTest(unittest.TestCase):
         args = BasicExample(**args_dict)
         self.assertEqual(parsed_args, args)
 
+    def test_parse_dict_extra_key(self):
+        parser = HfArgumentParser(BasicExample)
+
+        args_dict = {
+            "foo": 12,
+            "bar": 3.14,
+            "baz": "42",
+            "flag": True,
+            "extra": 42,
+        }
+
+        self.assertRaises(ValueError, parser.parse_dict, args_dict, allow_extra_keys=False)
+
     def test_integration_training_args(self):
         parser = HfArgumentParser(TrainingArguments)
         self.assertIsNotNone(parser)