Update app.py

app.py

@@ -6,6 +6,7 @@ import tempfile
 from typing import TypedDict, Annotated, Sequence
 from langchain_openai import ChatOpenAI
 from langchain_core.tools import tool
+from langchain_core.messages import HumanMessage, AIMessage
 from langchain_core.utils.function_calling import convert_to_openai_tool
 from langgraph.graph import StateGraph, END
 
@@ -15,11 +16,13 @@ os.environ['OPENAI_API_KEY'] = os.getenv("OPENAI_API_KEY")
 # Model Initialization
 model = ChatOpenAI(temperature=0)
 
+# Define the tool
 @tool
 def multiply(first_number: int, second_number: int):
     """Multiplies two numbers together and returns the result."""
     return first_number * second_number
 
+# Bind tool to model
 model_with_tools = model.bind(tools=[convert_to_openai_tool(multiply)])
 
 # State Setup
@@ -28,41 +31,60 @@ class AgentState(TypedDict):
 
 graph = StateGraph(AgentState)
 
+# Model Invocation
 def invoke_model(state):
-    question = state['messages'][-1]
+    """
+    Invoke the model and handle tool invocation logic.
+    """
+    # Extract the question as a string
+    question = state['messages'][-1].content if isinstance(state['messages'][-1], HumanMessage) else state['messages'][-1]
     response = model_with_tools.invoke(question)
-    # If no tool calls are found, return the raw response content
+
+    # If the response is plain text (no tool calls)
+    if isinstance(response, str):
+        return {"messages": [AIMessage(content=response)]}
+
+    # If no tool calls exist
     if not response.additional_kwargs.get("tool_calls", []):
-        return {"messages": [response.content]}
-    # Otherwise, return the response object as before
-    return {"messages": [response]}
+        return {"messages": [AIMessage(content=response.content)]}
 
+    # If tool calls are present, return the full response
+    return {"messages": [response]}
 
 graph.add_node("agent", invoke_model)
 
+# Tool Invocation
 def invoke_tool(state):
+    """
+    Invoke the 'multiply' tool if it's called by the model.
+    """
     tool_calls = state['messages'][-1].additional_kwargs.get("tool_calls", [])
     for tool_call in tool_calls:
-        if tool_call.get("function").get("name") == "multiply":
-            res = multiply.invoke(json.loads(tool_call.get("function").get("arguments")))
-            return {"messages": [f"Tool Result: {res}"]}
-    return {"messages": ["No tool input provided."]}
+        if tool_call.get("function", {}).get("name") == "multiply":
+            arguments = json.loads(tool_call.get("function").get("arguments"))
+            result = multiply.invoke(arguments)
+            return {"messages": [AIMessage(content=f"Tool Result: {result}")]}
+    return {"messages": [AIMessage(content="No valid tool input provided.")]}
 
 graph.add_node("tool", invoke_tool)
 graph.add_edge("tool", END)
 graph.set_entry_point("agent")
 
+# Router Logic
 def router(state):
-    calls = state['messages'][-1].additional_kwargs.get("tool_calls", [])
-    return "multiply" if calls else "end"
+    """
+    Decide whether to invoke a tool or return the response.
+    """
+    tool_calls = state['messages'][-1].additional_kwargs.get("tool_calls", [])
+    return "tool" if tool_calls else END
 
-graph.add_conditional_edges("agent", router, {"multiply": "tool", "end": END})
+graph.add_conditional_edges("agent", router, {"tool": "tool", END: END})
 app_graph = graph.compile()
 
 # Save graph visualization as an image
 with tempfile.NamedTemporaryFile(suffix=".png", delete=False) as tmpfile:
     graph_viz = app_graph.get_graph(xray=True)
-    tmpfile.write(graph_viz.draw_mermaid_png())  # Write binary image data to file
+    tmpfile.write(graph_viz.draw_mermaid_png())
     graph_image_path = tmpfile.name
 
 # Streamlit Interface
@@ -73,6 +95,7 @@ st.image(graph_image_path, caption="Workflow Visualization")
 
 tab1, tab2 = st.tabs(["Try Multiplication", "Ask General Queries"])
 
+# Multiplication Tool Tab
 with tab1:
     st.subheader("Try Multiplication")
     col1, col2 = st.columns(2)
@@ -84,9 +107,13 @@ with tab1:
 
     if st.button("Multiply"):
         question = f"What is {first_number} * {second_number}?"
-        output = app_graph.invoke({"messages": [question]})
-        st.success(output['messages'][-1])
+        try:
+            output = app_graph.invoke({"messages": [HumanMessage(content=question)]})
+            st.success(output['messages'][-1].content)
+        except Exception as e:
+            st.error(f"Error: {e}")
 
+# General Query Tab
 with tab2:
     st.subheader("General Query")
     user_input = st.text_input("Enter your question here")
@@ -94,14 +121,15 @@ with tab2:
     if st.button("Submit"):
         if user_input:
             try:
-                result = app_graph.invoke({"messages": [user_input]})
+                # Pass the user input as a HumanMessage
+                result = app_graph.invoke({"messages": [HumanMessage(content=user_input)]})
                 st.write("Response:")
-                st.success(result['messages'][-1])
+                st.success(result['messages'][-1].content)
             except Exception as e:
-                st.error("Something went wrong. Try again!")
+                st.error(f"Error: {e}")
         else:
             st.warning("Please enter a valid input.")
 
-
+# Sidebar for References
 st.sidebar.title("References")
-st.sidebar.markdown("1. [LangGraph Tool Calling](https://github.com/aritrasen87/LLM_RAG_Model_Deployment/blob/main/LangGraph_02_ToolCalling.ipynb)")
+st.sidebar.markdown("1. [LangGraph Tool Calling](https://github.com/aritrasen87/LLM_RAG_Model_Deployment/blob/main/LangGraph_02_ToolCalling.ipynb)")