refactor: HF API Embedders - use InferenceClient.feature_extraction instead of InferenceClient.post (#8794)

* HF API Embedders: refactoring

* rename variables

* rm leftovers

* rm pin

* rm unused import

* relnote

* warning with truncate/normalize and serverless inference API

* test that warnings are raised

Author: anakin87

Diff for: haystack/components/embedders/hugging_face_api_document_embedder.py

@@ -2,7 +2,7 @@
 #
 # SPDX-License-Identifier: Apache-2.0
 
-import json
+import warnings
 from typing import Any, Dict, List, Optional, Union
 
 from tqdm import tqdm
@@ -96,8 +96,8 @@ def __init__(
         token: Optional[Secret] = Secret.from_env_var(["HF_API_TOKEN", "HF_TOKEN"], strict=False),
         prefix: str = "",
         suffix: str = "",
-        truncate: bool = True,
-        normalize: bool = False,
+        truncate: Optional[bool] = True,
+        normalize: Optional[bool] = False,
         batch_size: int = 32,
         progress_bar: bool = True,
         meta_fields_to_embed: Optional[List[str]] = None,
@@ -124,13 +124,11 @@ def __init__(
             Applicable when `api_type` is `TEXT_EMBEDDINGS_INFERENCE`, or `INFERENCE_ENDPOINTS`
             if the backend uses Text Embeddings Inference.
             If `api_type` is `SERVERLESS_INFERENCE_API`, this parameter is ignored.
-            It is always set to `True` and cannot be changed.
         :param normalize:
             Normalizes the embeddings to unit length.
             Applicable when `api_type` is `TEXT_EMBEDDINGS_INFERENCE`, or `INFERENCE_ENDPOINTS`
             if the backend uses Text Embeddings Inference.
             If `api_type` is `SERVERLESS_INFERENCE_API`, this parameter is ignored.
-            It is always set to `False` and cannot be changed.
         :param batch_size:
             Number of documents to process at once.
         :param progress_bar:
@@ -239,18 +237,36 @@ def _embed_batch(self, texts_to_embed: List[str], batch_size: int) -> List[List[
         """
         Embed a list of texts in batches.
         """
+        truncate = self.truncate
+        normalize = self.normalize
+
+        if self.api_type == HFEmbeddingAPIType.SERVERLESS_INFERENCE_API:
+            if truncate is not None:
+                msg = "`truncate` parameter is not supported for Serverless Inference API. It will be ignored."
+                warnings.warn(msg)
+                truncate = None
+            if normalize is not None:
+                msg = "`normalize` parameter is not supported for Serverless Inference API. It will be ignored."
+                warnings.warn(msg)
+                normalize = None
 
         all_embeddings = []
         for i in tqdm(
             range(0, len(texts_to_embed), batch_size), disable=not self.progress_bar, desc="Calculating embeddings"
         ):
             batch = texts_to_embed[i : i + batch_size]
-            response = self._client.post(
-                json={"inputs": batch, "truncate": self.truncate, "normalize": self.normalize},
-                task="feature-extraction",
+
+            np_embeddings = self._client.feature_extraction(
+                # this method does not officially support list of strings, but works as expected
+                text=batch,  # type: ignore[arg-type]
+                truncate=truncate,
+                normalize=normalize,
             )
-            embeddings = json.loads(response.decode())
-            all_embeddings.extend(embeddings)
+
+            if np_embeddings.ndim != 2 or np_embeddings.shape[0] != len(batch):
+                raise ValueError(f"Expected embedding shape ({batch_size}, embedding_dim), got {np_embeddings.shape}")
+
+            all_embeddings.extend(np_embeddings.tolist())
 
         return all_embeddings
 

Diff for: haystack/components/embedders/hugging_face_api_text_embedder.py

@@ -2,7 +2,7 @@
 #
 # SPDX-License-Identifier: Apache-2.0
 
-import json
+import warnings
 from typing import Any, Dict, List, Optional, Union
 
 from haystack import component, default_from_dict, default_to_dict, logging
@@ -80,8 +80,8 @@ def __init__(
         token: Optional[Secret] = Secret.from_env_var(["HF_API_TOKEN", "HF_TOKEN"], strict=False),
         prefix: str = "",
         suffix: str = "",
-        truncate: bool = True,
-        normalize: bool = False,
+        truncate: Optional[bool] = True,
+        normalize: Optional[bool] = False,
     ):  # pylint: disable=too-many-positional-arguments
         """
         Creates a HuggingFaceAPITextEmbedder component.
@@ -104,13 +104,11 @@ def __init__(
             Applicable when `api_type` is `TEXT_EMBEDDINGS_INFERENCE`, or `INFERENCE_ENDPOINTS`
             if the backend uses Text Embeddings Inference.
             If `api_type` is `SERVERLESS_INFERENCE_API`, this parameter is ignored.
-            It is always set to `True` and cannot be changed.
         :param normalize:
             Normalizes the embeddings to unit length.
             Applicable when `api_type` is `TEXT_EMBEDDINGS_INFERENCE`, or `INFERENCE_ENDPOINTS`
             if the backend uses Text Embeddings Inference.
             If `api_type` is `SERVERLESS_INFERENCE_API`, this parameter is ignored.
-            It is always set to `False` and cannot be changed.
         """
         huggingface_hub_import.check()
 
@@ -198,12 +196,29 @@ def run(self, text: str):
                 "In case you want to embed a list of Documents, please use the HuggingFaceAPIDocumentEmbedder."
             )
 
+        truncate = self.truncate
+        normalize = self.normalize
+
+        if self.api_type == HFEmbeddingAPIType.SERVERLESS_INFERENCE_API:
+            if truncate is not None:
+                msg = "`truncate` parameter is not supported for Serverless Inference API. It will be ignored."
+                warnings.warn(msg)
+                truncate = None
+            if normalize is not None:
+                msg = "`normalize` parameter is not supported for Serverless Inference API. It will be ignored."
+                warnings.warn(msg)
+                normalize = None
+
         text_to_embed = self.prefix + text + self.suffix
 
-        response = self._client.post(
-            json={"inputs": [text_to_embed], "truncate": self.truncate, "normalize": self.normalize},
-            task="feature-extraction",
-        )
-        embedding = json.loads(response.decode())[0]
+        np_embedding = self._client.feature_extraction(text=text_to_embed, truncate=truncate, normalize=normalize)
+
+        error_msg = f"Expected embedding shape (1, embedding_dim) or (embedding_dim,), got {np_embedding.shape}"
+        if np_embedding.ndim > 2:
+            raise ValueError(error_msg)
+        if np_embedding.ndim == 2 and np_embedding.shape[0] != 1:
+            raise ValueError(error_msg)
+
+        embedding = np_embedding.flatten().tolist()
 
         return {"embedding": embedding}

Diff for: pyproject.toml

@@ -87,7 +87,7 @@ extra-dependencies = [
   "numba>=0.54.0", # This pin helps uv resolve the dependency tree. See https://github.com/astral-sh/uv/issues/7881
 
   "transformers[torch,sentencepiece]==4.47.1", # ExtractiveReader, TransformersSimilarityRanker, LocalWhisperTranscriber, HFGenerators...
-  "huggingface_hub>=0.27.0, <0.28.0",                   # Hugging Face API Generators and Embedders
+  "huggingface_hub>=0.27.0",                   # Hugging Face API Generators and Embedders
   "sentence-transformers>=3.0.0",              # SentenceTransformersTextEmbedder and SentenceTransformersDocumentEmbedder
   "langdetect",                                # TextLanguageRouter and DocumentLanguageClassifier
   "openai-whisper>=20231106",                  # LocalWhisperTranscriber

Diff for: releasenotes/notes/hf-embedders-feature-extraction-ea0421a8f76052f0.yaml

@@ -0,0 +1,5 @@
+---
+fixes:
+  - |
+    In the Hugging Face API embedders, the `InferenceClient.feature_extraction` method is now used instead of
+    `InferenceClient.post` to compute embeddings. This ensures a more robust and future-proof implementation.

Diff for: test/components/embedders/test_hugging_face_api_document_embedder.py

@@ -8,6 +8,8 @@
 import pytest
 from huggingface_hub.utils import RepositoryNotFoundError
 
+from numpy import array
+
 from haystack.components.embedders import HuggingFaceAPIDocumentEmbedder
 from haystack.dataclasses import Document
 from haystack.utils.auth import Secret
@@ -23,8 +25,8 @@ def mock_check_valid_model():
         yield mock
 
 
-def mock_embedding_generation(json, **kwargs):
-    response = str([[random.random() for _ in range(384)] for _ in range(len(json["inputs"]))]).encode()
+def mock_embedding_generation(text, **kwargs):
+    response = array([[random.random() for _ in range(384)] for _ in range(len(text))])
     return response
 
 
@@ -201,10 +203,10 @@ def test_prepare_texts_to_embed_w_suffix(self, mock_check_valid_model):
             "my_prefix document number 4 my_suffix",
         ]
 
-    def test_embed_batch(self, mock_check_valid_model):
+    def test_embed_batch(self, mock_check_valid_model, recwarn):
         texts = ["text 1", "text 2", "text 3", "text 4", "text 5"]
 
-        with patch("huggingface_hub.InferenceClient.post") as mock_embedding_patch:
+        with patch("huggingface_hub.InferenceClient.feature_extraction") as mock_embedding_patch:
             mock_embedding_patch.side_effect = mock_embedding_generation
 
             embedder = HuggingFaceAPIDocumentEmbedder(
@@ -223,6 +225,40 @@ def test_embed_batch(self, mock_check_valid_model):
             assert len(embedding) == 384
             assert all(isinstance(x, float) for x in embedding)
 
+        # Check that warnings about ignoring truncate and normalize are raised
+        assert len(recwarn) == 2
+        assert "truncate" in str(recwarn[0].message)
+        assert "normalize" in str(recwarn[1].message)
+
+    def test_embed_batch_wrong_embedding_shape(self, mock_check_valid_model):
+        texts = ["text 1", "text 2", "text 3", "text 4", "text 5"]
+
+        # embedding ndim != 2
+        with patch("huggingface_hub.InferenceClient.feature_extraction") as mock_embedding_patch:
+            mock_embedding_patch.return_value = array([0.1, 0.2, 0.3])
+
+            embedder = HuggingFaceAPIDocumentEmbedder(
+                api_type=HFEmbeddingAPIType.SERVERLESS_INFERENCE_API,
+                api_params={"model": "BAAI/bge-small-en-v1.5"},
+                token=Secret.from_token("fake-api-token"),
+            )
+
+            with pytest.raises(ValueError):
+                embedder._embed_batch(texts_to_embed=texts, batch_size=2)
+
+        # embedding ndim == 2 but shape[0] != len(batch)
+        with patch("huggingface_hub.InferenceClient.feature_extraction") as mock_embedding_patch:
+            mock_embedding_patch.return_value = array([[0.1, 0.2, 0.3], [0.4, 0.5, 0.6], [0.7, 0.8, 0.9]])
+
+            embedder = HuggingFaceAPIDocumentEmbedder(
+                api_type=HFEmbeddingAPIType.SERVERLESS_INFERENCE_API,
+                api_params={"model": "BAAI/bge-small-en-v1.5"},
+                token=Secret.from_token("fake-api-token"),
+            )
+
+            with pytest.raises(ValueError):
+                embedder._embed_batch(texts_to_embed=texts, batch_size=2)
+
     def test_run_wrong_input_format(self, mock_check_valid_model):
         embedder = HuggingFaceAPIDocumentEmbedder(
             api_type=HFEmbeddingAPIType.SERVERLESS_INFERENCE_API, api_params={"model": "BAAI/bge-small-en-v1.5"}
@@ -252,7 +288,7 @@ def test_run(self, mock_check_valid_model):
             Document(content="A transformer is a deep learning architecture", meta={"topic": "ML"}),
         ]
 
-        with patch("huggingface_hub.InferenceClient.post") as mock_embedding_patch:
+        with patch("huggingface_hub.InferenceClient.feature_extraction") as mock_embedding_patch:
             mock_embedding_patch.side_effect = mock_embedding_generation
 
             embedder = HuggingFaceAPIDocumentEmbedder(
@@ -268,16 +304,14 @@ def test_run(self, mock_check_valid_model):
             result = embedder.run(documents=docs)
 
             mock_embedding_patch.assert_called_once_with(
-                json={
-                    "inputs": [
-                        "prefix Cuisine | I love cheese suffix",
-                        "prefix ML | A transformer is a deep learning architecture suffix",
-                    ],
-                    "truncate": True,
-                    "normalize": False,
-                },
-                task="feature-extraction",
+                text=[
+                    "prefix Cuisine | I love cheese suffix",
+                    "prefix ML | A transformer is a deep learning architecture suffix",
+                ],
+                truncate=None,
+                normalize=None,
             )
+
         documents_with_embeddings = result["documents"]
 
         assert isinstance(documents_with_embeddings, list)
@@ -294,7 +328,7 @@ def test_run_custom_batch_size(self, mock_check_valid_model):
             Document(content="A transformer is a deep learning architecture", meta={"topic": "ML"}),
         ]
 
-        with patch("huggingface_hub.InferenceClient.post") as mock_embedding_patch:
+        with patch("huggingface_hub.InferenceClient.feature_extraction") as mock_embedding_patch:
             mock_embedding_patch.side_effect = mock_embedding_generation
 
             embedder = HuggingFaceAPIDocumentEmbedder(

Diff for: test/components/embedders/test_hugging_face_api_text_embedder.py

@@ -7,7 +7,7 @@
 import random
 import pytest
 from huggingface_hub.utils import RepositoryNotFoundError
-
+from numpy import array
 from haystack.components.embedders import HuggingFaceAPITextEmbedder
 from haystack.utils.auth import Secret
 from haystack.utils.hf import HFEmbeddingAPIType
@@ -21,11 +21,6 @@ def mock_check_valid_model():
         yield mock
 
 
-def mock_embedding_generation(json, **kwargs):
-    response = str([[random.random() for _ in range(384)] for _ in range(len(json["inputs"]))]).encode()
-    return response
-
-
 class TestHuggingFaceAPITextEmbedder:
     def test_init_invalid_api_type(self):
         with pytest.raises(ValueError):
@@ -141,9 +136,9 @@ def test_run_wrong_input_format(self, mock_check_valid_model):
         with pytest.raises(TypeError):
             embedder.run(text=list_integers_input)
 
-    def test_run(self, mock_check_valid_model):
-        with patch("huggingface_hub.InferenceClient.post") as mock_embedding_patch:
-            mock_embedding_patch.side_effect = mock_embedding_generation
+    def test_run(self, mock_check_valid_model, recwarn):
+        with patch("huggingface_hub.InferenceClient.feature_extraction") as mock_embedding_patch:
+            mock_embedding_patch.return_value = array([[random.random() for _ in range(384)]])
 
             embedder = HuggingFaceAPITextEmbedder(
                 api_type=HFEmbeddingAPIType.SERVERLESS_INFERENCE_API,
@@ -156,13 +151,40 @@ def test_run(self, mock_check_valid_model):
             result = embedder.run(text="The food was delicious")
 
             mock_embedding_patch.assert_called_once_with(
-                json={"inputs": ["prefix The food was delicious suffix"], "truncate": True, "normalize": False},
-                task="feature-extraction",
+                text="prefix The food was delicious suffix", truncate=None, normalize=None
             )
 
         assert len(result["embedding"]) == 384
         assert all(isinstance(x, float) for x in result["embedding"])
 
+        # Check that warnings about ignoring truncate and normalize are raised
+        assert len(recwarn) == 2
+        assert "truncate" in str(recwarn[0].message)
+        assert "normalize" in str(recwarn[1].message)
+
+    def test_run_wrong_embedding_shape(self, mock_check_valid_model):
+        # embedding ndim > 2
+        with patch("huggingface_hub.InferenceClient.feature_extraction") as mock_embedding_patch:
+            mock_embedding_patch.return_value = array([[[0.1, 0.2, 0.3], [0.4, 0.5, 0.6], [0.7, 0.8, 0.9]]])
+
+            embedder = HuggingFaceAPITextEmbedder(
+                api_type=HFEmbeddingAPIType.SERVERLESS_INFERENCE_API, api_params={"model": "BAAI/bge-small-en-v1.5"}
+            )
+
+            with pytest.raises(ValueError):
+                embedder.run(text="The food was delicious")
+
+        # embedding ndim == 2 but shape[0] != 1
+        with patch("huggingface_hub.InferenceClient.feature_extraction") as mock_embedding_patch:
+            mock_embedding_patch.return_value = array([[0.1, 0.2, 0.3], [0.4, 0.5, 0.6]])
+
+            embedder = HuggingFaceAPITextEmbedder(
+                api_type=HFEmbeddingAPIType.SERVERLESS_INFERENCE_API, api_params={"model": "BAAI/bge-small-en-v1.5"}
+            )
+
+            with pytest.raises(ValueError):
+                embedder.run(text="The food was delicious")
+
     @pytest.mark.flaky(reruns=5, reruns_delay=5)
     @pytest.mark.integration
     @pytest.mark.skipif(