Create app.py

app.py

@@ -0,0 +1,75 @@
+import os
+import gradio as gr
+from langchain_openai import ChatOpenAI
+from langchain_core.messages import HumanMessage
+from langgraph.checkpoint.memory import MemorySaver
+from langgraph.graph import START, MessagesState, StateGraph
+
+def create_chat_app(api_key):
+    # Initialize the chat model
+    llm = ChatOpenAI(
+        model="gpt-4o-mini",
+        api_key=api_key,
+        temperature=0
+    )[1]
+
+    # Define the graph
+    workflow = StateGraph(state_schema=MessagesState)
+
+    # Define the function that calls the model
+    def call_model(state: MessagesState):
+        response = llm.invoke(state["messages"])
+        return {"messages": response}[1]
+
+    # Add node and edge to graph
+    workflow.add_edge(START, "model")
+    workflow.add_node("model", call_model)[1]
+
+    # Add memory
+    memory = MemorySaver()
+    return workflow.compile(checkpointer=memory)[1]
+
+def chat(message, history, api_key, thread_id):
+    if not api_key:
+        return "Please enter your OpenAI API key first."
+    
+    try:
+        # Create chat application if not exists
+        app = create_chat_app(api_key)
+        
+        # Configure thread
+        config = {"configurable": {"thread_id": thread_id}}[1]
+        
+        # Prepare input message
+        input_messages = [HumanMessage(message)]
+        
+        # Get response
+        output = app.invoke({"messages": input_messages}, config)[1]
+        
+        return output["messages"][-1].content
+    except Exception as e:
+        return f"Error: {str(e)}"
+
+# Create Gradio interface
+with gr.Blocks() as demo:
+    gr.Markdown("# LangChain Chat with Message History")
+    
+    with gr.Row():
+        api_key = gr.Textbox(
+            label="OpenAI API Key", 
+            placeholder="Enter your OpenAI API key",
+            type="password"
+        )
+        thread_id = gr.Textbox(
+            label="Thread ID",
+            value="default_thread",
+            placeholder="Enter a unique thread ID"
+        )
+    
+    chatbot = gr.ChatInterface(
+        fn=lambda message, history: chat(message, history, api_key.value, thread_id.value),
+        title="Chat with GPT-4o-mini"
+    )[2]
+
+# Launch the application
+demo.launch()