feature: adds RedisVectorStore::from_existing_index class method

libs/redis/langchain_redis/vectorstores.py

@@ -269,6 +269,20 @@ def from_documents(
             **kwargs,
         )
 
+    @classmethod
+    def from_existing_index(
+        cls,
+        index_name: str,
+        embedding: Embeddings,
+        **kwargs: Any,
+    ) -> RedisVectorStore:
+        """Create a RedisVectorStore from an existing Redis Search Index."""
+        config = RedisConfig.from_kwargs(**kwargs)
+        config.index_name = index_name
+        config.from_existing = True
+
+        return RedisVectorStore(embedding, config=config)
+
     def delete(self, ids: Optional[List[str]] = None, **kwargs: Any) -> Optional[bool]:
         """Delete keys from the vector store."""
         return self._index.delete(ids)

libs/redis/tests/integration_tests/test_vectorstores.py

@@ -137,6 +137,33 @@ def test_redis_from_existing(texts: List[str], redis_url: str) -> None:
     assert output == TEST_SINGLE_RESULT
 
 
+def test_redis_from_existing_with_class_method(
+    texts: List[str], redis_url: str
+) -> None:
+    """Test adding a new document"""
+    # Create a unique index name for testing
+    index_name = f"test_index_{str(ULID())}"
+    vector_store = RedisVectorStore.from_texts(
+        texts,
+        OpenAIEmbeddings(),
+        index_name=index_name,
+        key_prefix="tst3",
+        redis_url=redis_url,
+    )
+
+    # write schema for the next test
+    vector_store.index.schema.to_yaml("test_schema.yml")
+
+    # Test creating from an existing
+    vector_store2 = RedisVectorStore.from_existing_index(
+        index_name=index_name,
+        embedding=OpenAIEmbeddings(),
+        redis_url=redis_url,
+    )
+    output = vector_store2.similarity_search("foo", k=1, return_metadata=False)
+    assert output == TEST_SINGLE_RESULT
+
+
 def test_redis_add_texts_to_existing(redis_url: str) -> None:
     """Test adding a new document"""
     # Test creating from an existing with yaml from file