src/streamlit_app.py

import streamlit as st
from pathlib import Path
from langchain.agents import create_sql_agent
from langchain.sql_database import SQLDatabase
from langchain.agents.agent_types import AgentType
from langchain.callbacks import StreamlitCallbackHandler
from langchain_community.agent_toolkits.sql.toolkit import SQLDatabaseToolkit
from sqlalchemy import create_engine
import sqlite3
from langchain_groq import ChatGroq

st.set_page_config(page_title="LangChain: Chat with SQL DB", page_icon="🦜")
st.title("🦜 LangChain: Chat with SQL DB")

LOCALDB = "USE_LOCALDB"
MYSQL = "USE_MYSQL"

radio_opt = ["Use SQLLite 3 Database- STUDENT.db", "Connect to you MySQL Database"]
selected_opt = st.sidebar.radio(label="Choose the DB which you want to chat", options=radio_opt)

if radio_opt.index(selected_opt) == 1:
    db_uri = MYSQL
    mysql_host = st.sidebar.text_input("Provide MySQL Host")
    mysql_user = st.sidebar.text_input("MYSQL User")
    mysql_password = st.sidebar.text_input("MYSQL password (leave blank if no password)", type="password")
    mysql_db = st.sidebar.text_input("MySQL database")
else:
    db_uri = LOCALDB

# Get API key from user input
api_key = st.sidebar.text_input(label="GROQ API Key", type="password")

if not api_key:
    st.info("Please add the Groq API key to continue")
    st.stop()

if db_uri == MYSQL and not all([mysql_host, mysql_user, mysql_db]):
    st.info("Please enter all required MySQL database information")
    st.stop()

# LLM model - using user-provided API key
llm = ChatGroq(groq_api_key=api_key, model_name="llama-3.1-8b-instant", streaming=True)

@st.cache_resource(ttl="2h")
def configure_db(db_uri, mysql_host=None, mysql_user=None, mysql_password=None, mysql_db=None):
    if db_uri == LOCALDB:
        dbfilepath = (Path(__file__).parent/"STUDENT.db").absolute()
        print(dbfilepath)
        creator = lambda: sqlite3.connect(f"file:{dbfilepath}?mode=ro", uri=True)
        return SQLDatabase(create_engine("sqlite:///", creator=creator))
    elif db_uri == MYSQL:
        if not (mysql_host and mysql_user and mysql_db):
            st.error("Please provide MySQL host, user, and database name.")
            st.stop()
                
        # Handle optional password
        if mysql_password:
            connection_string = f"mysql+mysqlconnector://{mysql_user}:{mysql_password}@{mysql_host}/{mysql_db}"
        else:
            connection_string = f"mysql+mysqlconnector://{mysql_user}@{mysql_host}/{mysql_db}"
                
        return SQLDatabase(create_engine(connection_string))

# Configure database
try:
    if db_uri == MYSQL:
        db = configure_db(db_uri, mysql_host, mysql_user, mysql_password, mysql_db)
    else:
        db = configure_db(db_uri)
except Exception as e:
    st.error(f"Error connecting to database: {str(e)}")
    st.stop()

# Toolkit
toolkit = SQLDatabaseToolkit(db=db, llm=llm)
agent = create_sql_agent(
    llm=llm,
    toolkit=toolkit,
    verbose=True,
    agent_type=AgentType.ZERO_SHOT_REACT_DESCRIPTION
)

if "messages" not in st.session_state or st.sidebar.button("Clear message history"):
    st.session_state["messages"] = [{"role": "assistant", "content": "How can I help you?"}]

for msg in st.session_state.messages:
    st.chat_message(msg["role"]).write(msg["content"])

user_query = st.chat_input(placeholder="Ask anything from the database")

if user_query:
    st.session_state.messages.append({"role": "user", "content": user_query})
    st.chat_message("user").write(user_query)
        
    with st.chat_message("assistant"):
        try:
            streamlit_callback = StreamlitCallbackHandler(st.container())
            response = agent.run(user_query, callbacks=[streamlit_callback])
            st.session_state.messages.append({"role": "assistant", "content": response})
            st.write(response)
        except Exception as e:
            error_message = f"An error occurred: {str(e)}"
            st.error(error_message)
            st.session_state.messages.append({"role": "assistant", "content": error_message})