Weaviate: Batch embed texts (#5903)

When a custom Embeddings object is set, embed all given texts in a batch
instead of passing them through individually. Any code calling add_texts
can then appropriately size the chunks of texts that are passed through
to take full advantage of the hardware it's running on.

langchain/vectorstores/weaviate.py

@@ -135,6 +135,12 @@ class Weaviate(VectorStore):
         from weaviate.util import get_valid_uuid
 
         ids = []
+        embeddings: Optional[List[List[float]]] = None
+        if self._embedding:
+            if not isinstance(texts, list):
+                texts = list(texts)
+            embeddings = self._embedding.embed_documents(texts)
+
         with self._client.batch as batch:
             for i, text in enumerate(texts):
                 data_properties = {self._text_key: text}
@@ -152,15 +158,11 @@ class Weaviate(VectorStore):
                 elif "ids" in kwargs:
                     _id = kwargs["ids"][i]
 
-                if self._embedding is not None:
-                    vector = self._embedding.embed_documents([text])[0]
-                else:
-                    vector = None
                 batch.add_data_object(
                     data_object=data_properties,
                     class_name=self._index_name,
                     uuid=_id,
-                    vector=vector,
+                    vector=embeddings[i] if embeddings else None,
                 )
                 ids.append(_id)
         return ids