Cli root model support (#677)

Author: kschwab

pydantic_settings/sources/providers/cli.py

@@ -956,7 +956,7 @@ def _add_parser_args(
 
                 self._convert_bool_flag(arg.kwargs, field_info, model_default)
 
-                if arg.is_parser_submodel:
+                if arg.is_parser_submodel and not getattr(field_info.annotation, '__pydantic_root_model__', False):
                     self._add_parser_submodels(
                         parser,
                         model,
@@ -1107,6 +1107,7 @@ def _add_parser_submodels(
             model_group_kwargs['description'] = CLI_SUPPRESS
         if not self.cli_avoid_json:
             added_args.append(arg_names[0])
+            kwargs['required'] = False
             kwargs['nargs'] = '?'
             kwargs['const'] = '{}'
             kwargs['help'] = (
@@ -1205,8 +1206,12 @@ def _metavar_format_recurse(self, obj: Any) -> str:
             )
         elif obj is type(None):
             return self.cli_parse_none_str
-        elif is_model_class(obj):
-            return 'JSON'
+        elif is_model_class(obj) or is_pydantic_dataclass(obj):
+            return (
+                self._metavar_format_recurse(_get_model_fields(obj)['root'].annotation)
+                if getattr(obj, '__pydantic_root_model__', False)
+                else 'JSON'
+            )
         elif isinstance(obj, type):
             return obj.__qualname__
         else:

tests/test_source_cli.py

@@ -19,6 +19,7 @@
     DirectoryPath,
     Discriminator,
     Field,
+    RootModel,
     Tag,
     ValidationError,
     field_validator,
@@ -1778,20 +1779,31 @@ class Settings(BaseSettings):
 
 
 def test_cli_enforce_required(env):
+    class MyRootModel(RootModel[str]):
+        root: str
+
     class Settings(BaseSettings, cli_exit_on_error=False):
         my_required_field: str
+        my_root_model_required_field: MyRootModel
 
     env.set('MY_REQUIRED_FIELD', 'hello from environment')
+    env.set('MY_ROOT_MODEL_REQUIRED_FIELD', 'hi from environment')
 
     assert Settings(_cli_parse_args=[], _cli_enforce_required=False).model_dump() == {
-        'my_required_field': 'hello from environment'
+        'my_required_field': 'hello from environment',
+        'my_root_model_required_field': 'hi from environment',
     }
 
     with pytest.raises(
         SettingsError, match='error parsing CLI: the following arguments are required: --my_required_field'
     ):
         Settings(_cli_parse_args=[], _cli_enforce_required=True).model_dump()
 
+    with pytest.raises(
+        SettingsError, match='error parsing CLI: the following arguments are required: --my_root_model_required_field'
+    ):
+        Settings(_cli_parse_args=['--my_required_field', 'hello from cli'], _cli_enforce_required=True).model_dump()
+
 
 def test_cli_exit_on_error(capsys, monkeypatch):
     class Settings(BaseSettings, cli_parse_args=True): ...