Langchain and Chromadb - how to incorporate a PromptTemplate

Question

I have the following LangChain code that checks the chroma vectorstore and extracts the answers from the stored docs - how do I incorporate a Prompt template to create some context , such as the following:

sales_template = """You are customer services and you need to help people.
{context}
Question: {question}"""
SALES_PROMPT = PromptTemplate(
    template=sales_template, input_variables=["context", "question"]
)

How do I incorporate the above into the below?

#Embedding Text Using Langchain
from langchain.embeddings import SentenceTransformerEmbeddings
embeddings = SentenceTransformerEmbeddings(model_name="all-MiniLM-L6-v2")

# Creating Vector Store with Chroma DB
from langchain.vectorstores import Chroma
#db = Chroma.from_documents(docs, embeddings)
db = Chroma(persist_directory="./chroma_db", embedding_function=embeddings)
# docs = db3.similarity_search(query)
# print(docs[0].page_content)

#Using OpenAI Large Language Models (LLM) with Chroma DB
import os
os.environ["OPENAI_API_KEY"] =  'sk-12345678910'

from langchain.chat_models import ChatOpenAI
model_name = "gpt-3.5-turbo"
llm = ChatOpenAI(model_name=model_name)

#Extracting Answers from Documents

from langchain.chains.question_answering import load_qa_chain
chain = load_qa_chain(llm, chain_type="stuff",verbose=True)

query = "What does Neil do for work?"
matching_docs = db.similarity_search(query)
answer =  chain.run(input_documents=matching_docs, question=query)
print(answer)

Answer 1

you can try as below

        sales_template = """You are customer services and you need to help people.
        {context}
        Question: {question}"""


        chain = RetrievalQAWithSourcesChain.from_chain_type(
            llm=OpenAI(temperature=0),
            chain_type="stuff",
            retriever=docsearch.as_retriever(search_type="similarity", search_kwargs={"k":2}),
            chain_type_kwargs={
                "prompt": PromptTemplate(
                    template=sales_template,
                    input_variables=["context", "question"],
                ),
            },
        )