rag_dspy.py

# rag_dspy.py

import dspy
from dspy_qdrant import QdrantRM
from qdrant_client import QdrantClient, models
from dotenv import load_dotenv
import os

load_dotenv() 
# DSPy setup
lm = dspy.LM("gpt-4", max_tokens=512,api_key=os.environ.get("OPENAI_API_KEY"))
client = QdrantClient(url=os.environ.get("QDRANT_CLOUD_URL"), api_key=os.environ.get("QDRANT_API_KEY"))
collection_name = "medical_chat_bot"
rm = QdrantRM(
    qdrant_collection_name=collection_name, 
    qdrant_client=client, 
    vector_name="dense",                 # <-- MATCHES your vector field in upsert
    document_field="passage_text",        # <-- MATCHES your payload field in upsert
    k=20)

dspy.settings.configure(lm=lm, rm=rm)

# Manual reranker using ColBERT multivector field
# Manual reranker using Qdrant’s native prefetch + ColBERT query
def rerank_with_colbert(query_text):
    from fastembed import TextEmbedding, LateInteractionTextEmbedding

    # Encode query once with both models
    dense_model = TextEmbedding("BAAI/bge-small-en")
    colbert_model = LateInteractionTextEmbedding("colbert-ir/colbertv2.0")

    dense_query = list(dense_model.embed(query_text))[0]
    colbert_query = list(colbert_model.embed(query_text))[0]

    # Combined query: retrieve with dense, rerank with ColBERT
    results = client.query_points(
        collection_name=collection_name,
        prefetch=models.Prefetch(
            query=dense_query,
            using="dense"
        ),
        query=colbert_query,
        using="colbert",
        limit=5,
        with_payload=True
    )
    
    points = results.points
    docs = []

    for point in points:
        docs.append(point.payload['passage_text'])

    return docs

# DSPy Signature and Module
class MedicalAnswer(dspy.Signature):
    question = dspy.InputField(desc="The medical question to answer")
    context = dspy.OutputField(desc="The answer to the medical question")
    final_answer = dspy.OutputField(desc="The answer to the medical question")

class MedicalRAG(dspy.Module):
    def __init__(self):
        super().__init__()

    def forward(self, question):
        reranked_docs = rerank_with_colbert(question)

        context_str = "\n".join(reranked_docs)

        return dspy.ChainOfThought(MedicalAnswer)(
            question=question,
            context=context_str
        )