chat_simple.py

import getpass
import os
from langchain.chat_models import init_chat_model
from langgraph.checkpoint.memory import MemorySaver
from langgraph.graph import START, MessagesState, StateGraph
from langchain_core.messages import AIMessage
from langchain_core.messages import HumanMessage


os.environ["GOOGLE_API_KEY"] = "AIzaSyDf2mmEYdHTVRpJ8TO5MZKEQ8jr9FhEALQ"

model = init_chat_model("gemini-2.0-flash", model_provider="google_genai")

# Define a new graph
workflow = StateGraph(state_schema=MessagesState)


# Define the function that calls the model
def call_model(state: MessagesState):
    response = model.invoke(state["messages"])
    return {"messages": response}


# Define the (single) node in the graph
workflow.add_edge(START, "model")
workflow.add_node("model", call_model)

# Add memory
memory = MemorySaver()
app = workflow.compile(checkpointer=memory)

# config = {"configurable": {"thread_id": "abc123"}}
# query = "Hi! I'm Bob."

# input_messages = [HumanMessage(query)]
# output = app.invoke({"messages": input_messages}, config)
# output["messages"][-1].pretty_print()  # output contains all messages in state


def get_response(query, config):

    input_messages = [HumanMessage(query)]
    output = app.invoke({"messages": input_messages}, config)
    content = output["messages"][-1].content 
    
    return content

if __name__ == "__main__":

    query = input("Enter your query: ")
    config = {"configurable": {"thread_id": "abc123"}}
    response = get_response(query, config)
    print(response)