parse arguments from dict (#4869)

* add parse_dict to parse arguments from dict

* add unit test for parse_dict

src/transformers/hf_argparser.py

@@ -158,3 +158,16 @@ class HfArgumentParser(ArgumentParser):
             obj = dtype(**inputs)
             outputs.append(obj)
         return (*outputs,)
+
+    def parse_dict(self, args: dict) -> Tuple[DataClass, ...]:
+        """
+        Alternative helper method that does not use `argparse` at all,
+        instead uses a dict and populating the dataclass types.
+        """
+        outputs = []
+        for dtype in self.dataclass_types:
+            keys = {f.name for f in dataclasses.fields(dtype)}
+            inputs = {k: v for k, v in args.items() if k in keys}
+            obj = dtype(**inputs)
+            outputs.append(obj)
+        return (*outputs,)

tests/test_hf_argparser.py

@@ -152,6 +152,20 @@ class HfArgumentParserTest(unittest.TestCase):
         args = parser.parse_args("--foo 12 --bar 3.14 --baz 42 --ces a b c --des 1 2 3".split())
         self.assertEqual(args, Namespace(foo=12, bar=3.14, baz="42", ces=["a", "b", "c"], des=[1, 2, 3]))
 
+    def test_parse_dict(self):
+        parser = HfArgumentParser(BasicExample)
+
+        args_dict = {
+            "foo": 12,
+            "bar": 3.14,
+            "baz": "42",
+            "flag": True,
+        }
+
+        parsed_args = parser.parse_dict(args_dict)[0]
+        args = BasicExample(**args_dict)
+        self.assertEqual(parsed_args, args)
+
     def test_integration_training_args(self):
         parser = HfArgumentParser(TrainingArguments)
         self.assertIsNotNone(parser)