Add RAG input types (#12684)

Co-authored-by: Erick Friis <erick@langchain.dev>

templates/rag-pinecone-multi-query/rag_pinecone_multi_query/chain.py

@@ -3,6 +3,7 @@ import os
 from langchain.chat_models import ChatOpenAI
 from langchain.embeddings import OpenAIEmbeddings
 from langchain.prompts import ChatPromptTemplate
+from langchain.pydantic_v1 import BaseModel
 from langchain.retrievers.multi_query import MultiQueryRetriever
 from langchain.schema.output_parser import StrOutputParser
 from langchain.schema.runnable import RunnableParallel, RunnablePassthrough
@@ -55,3 +56,11 @@ chain = (
     | model
     | StrOutputParser()
 )
+
+
+# Add typing for input
+class Question(BaseModel):
+    __root__: str
+
+
+chain = chain.with_types(input_type=Question)