Recursive filter_none in Inference Providers (#3178)

* Recursive filter_none in Inference Providers

* filter none values from messages as well

* update filter_none and add test cases

* don't drop empty dicts in list

* better typing and refactor logic into a list of comrpehension

---------

Co-authored-by: Celina Hanouti <[email protected]>

Author: Wauplin

src/huggingface_hub/inference/_providers/_common.py

@@ -1,9 +1,10 @@
 from functools import lru_cache
-from typing import Any, Dict, List, Optional, Union
+from typing import Any, Dict, List, Optional, Union, overload
 
 from huggingface_hub import constants
 from huggingface_hub.hf_api import InferenceProviderMapping
 from huggingface_hub.inference._common import RequestParameters
+from huggingface_hub.inference._generated.types.chat_completion import ChatCompletionInputMessage
 from huggingface_hub.utils import build_hf_headers, get_token, logging
 
 
@@ -36,8 +37,30 @@
 }
 
 
-def filter_none(d: Dict[str, Any]) -> Dict[str, Any]:
-    return {k: v for k, v in d.items() if v is not None}
+@overload
+def filter_none(obj: Dict[str, Any]) -> Dict[str, Any]: ...
+@overload
+def filter_none(obj: List[Any]) -> List[Any]: ...
+
+
+def filter_none(obj: Union[Dict[str, Any], List[Any]]) -> Union[Dict[str, Any], List[Any]]:
+    if isinstance(obj, dict):
+        cleaned: Dict[str, Any] = {}
+        for k, v in obj.items():
+            if v is None:
+                continue
+            if isinstance(v, (dict, list)):
+                v = filter_none(v)
+                # remove empty nested dicts
+                if isinstance(v, dict) and not v:
+                    continue
+            cleaned[k] = v
+        return cleaned
+
+    if isinstance(obj, list):
+        return [filter_none(v) if isinstance(v, (dict, list)) else v for v in obj]
+
+    raise ValueError(f"Expected dict or list, got {type(obj)}")
 
 
 class TaskProviderHelper:
@@ -224,9 +247,12 @@ def _prepare_route(self, mapped_model: str, api_key: str) -> str:
         return "/v1/chat/completions"
 
     def _prepare_payload_as_dict(
-        self, inputs: Any, parameters: Dict, provider_mapping_info: InferenceProviderMapping
+        self,
+        inputs: List[Union[Dict, ChatCompletionInputMessage]],
+        parameters: Dict,
+        provider_mapping_info: InferenceProviderMapping,
     ) -> Optional[Dict]:
-        return {"messages": inputs, **filter_none(parameters), "model": provider_mapping_info.provider_id}
+        return filter_none({"messages": inputs, **parameters, "model": provider_mapping_info.provider_id})
 
 
 class BaseTextGenerationTask(TaskProviderHelper):

src/huggingface_hub/inference/_providers/hf_inference.py

@@ -75,7 +75,7 @@ def _prepare_payload_as_bytes(
         provider_mapping_info: InferenceProviderMapping,
         extra_payload: Optional[Dict],
     ) -> Optional[bytes]:
-        parameters = filter_none({k: v for k, v in parameters.items() if v is not None})
+        parameters = filter_none(parameters)
         extra_payload = extra_payload or {}
         has_parameters = len(parameters) > 0 or len(extra_payload) > 0
 

tests/test_inference_providers.py

@@ -13,6 +13,7 @@
     BaseConversationalTask,
     BaseTextGenerationTask,
     TaskProviderHelper,
+    filter_none,
     recursive_merge,
 )
 from huggingface_hub.inference._providers.black_forest_labs import BlackForestLabsTextToImageTask
@@ -1152,6 +1153,98 @@ def test_prepare_payload(self):
             "model": "test-provider-id",
         }
 
+    @pytest.mark.parametrize(
+        "raw_messages, expected_messages",
+        [
+            (
+                [
+                    {
+                        "role": "assistant",
+                        "content": "",
+                        "tool_calls": None,
+                    }
+                ],
+                [
+                    {
+                        "role": "assistant",
+                        "content": "",
+                    }
+                ],
+            ),
+            (
+                [
+                    {
+                        "role": "assistant",
+                        "content": None,
+                        "tool_calls": [
+                            {
+                                "id": "call_1",
+                                "type": "function",
+                                "function": {
+                                    "name": "get_current_weather",
+                                    "arguments": '{"location": "San Francisco, CA", "unit": "celsius"}',
+                                },
+                            },
+                        ],
+                    },
+                    {
+                        "role": "tool",
+                        "content": "pong",
+                        "tool_call_id": "abc123",
+                        "name": "dummy_tool",
+                        "tool_calls": None,
+                    },
+                ],
+                [
+                    {
+                        "role": "assistant",
+                        "tool_calls": [
+                            {
+                                "id": "call_1",
+                                "type": "function",
+                                "function": {
+                                    "name": "get_current_weather",
+                                    "arguments": '{"location": "San Francisco, CA", "unit": "celsius"}',
+                                },
+                            }
+                        ],
+                    },
+                    {
+                        "role": "tool",
+                        "content": "pong",
+                        "tool_call_id": "abc123",
+                        "name": "dummy_tool",
+                    },
+                ],
+            ),
+        ],
+    )
+    def test_prepare_payload_filters_messages(self, raw_messages, expected_messages):
+        helper = BaseConversationalTask(provider="test-provider", base_url="https://api.test.com")
+
+        parameters = {
+            "temperature": 0.2,
+            "max_tokens": None,
+            "top_p": None,
+        }
+
+        payload = helper._prepare_payload_as_dict(
+            inputs=raw_messages,
+            parameters=parameters,
+            provider_mapping_info=InferenceProviderMapping(
+                provider="test-provider",
+                hf_model_id="test-model",
+                providerId="test-provider-id",
+                task="conversational",
+                status="live",
+            ),
+        )
+
+        assert payload["messages"] == expected_messages
+        assert payload["temperature"] == 0.2
+        assert "max_tokens" not in payload
+        assert "top_p" not in payload
+
 
 class TestBaseTextGenerationTask:
     def test_prepare_route(self):
@@ -1236,6 +1329,36 @@ def test_recursive_merge(dict1: Dict, dict2: Dict, expected: Dict):
     assert dict2 == initial_dict2
 
 
+@pytest.mark.parametrize(
+    "data, expected",
+    [
+        ({}, {}),  # empty dictionary remains empty
+        ({"a": 1, "b": None, "c": 3}, {"a": 1, "c": 3}),  # remove None at root level
+        ({"a": None, "b": {"x": None, "y": 2}}, {"b": {"y": 2}}),  # remove nested None
+        ({"a": {"b": {"c": None}}}, {}),  # remove empty nested dict
+        (
+            {"a": "", "b": {"x": {"y": None}, "z": 0}, "c": []},  # do not remove 0, [] and "" values
+            {"a": "", "b": {"z": 0}, "c": []},
+        ),
+        (
+            {"a": [0, 1, None]},  # do not remove None in lists
+            {"a": [0, 1, None]},
+        ),
+        # dicts inside list are cleaned, list level None kept
+        ({"a": [{"x": None, "y": 1}, None]}, {"a": [{"y": 1}, None]}),
+        # remove every None that is the value of a dict key
+        (
+            [None, {"x": None, "y": 5}, [None, 6]],
+            [None, {"y": 5}, [None, 6]],
+        ),
+        ({"a": [None, {"x": None}]}, {"a": [None, {}]}),
+    ],
+)
+def test_filter_none(data: Dict, expected: Dict):
+    """Test that filter_none removes None values from nested dictionaries."""
+    assert filter_none(data) == expected
+
+
 def test_get_provider_helper_auto(mocker):
     """Test the 'auto' provider selection logic."""