Looping Graph 🌌

Objectives ✅

Implement looping logic to route the flow of data to different nodes.
Create a single condition edge to handle decision-making and control graph flow.

from typing import TypedDict, List
import random
from langgraph.graph import StateGraph, START, END
 
class AgentState(TypedDict):
    name: str
    number: List[int]
    counter: int

def greeting_node(state: AgentState) -> AgentState:
    """Greet the user and ask for their name."""
 
    state['name'] = f"Hi, there, {state['name']}"
    state["counter"] = 0
 
    return state
 
def random_node(state: AgentState) -> AgentState:
    """Generate a random number and add it to the list."""
 
    state['number'].append(random.randint(1, 100))
    state["counter"] += 1
 
    return state
 
 
def should_continue(state: AgentState) -> AgentState:
    """Decide whether to continue looping based on the counter."""
 
    if state["counter"] < 5:
        print("ENTERING LOOP", state["counter"])
        return "loop"
    else:
        print("EXITING LOOP", state["counter"])
        return "end"

graph = StateGraph(AgentState)
 
graph.add_node("greeting_node", greeting_node)
graph.add_node("random_node", random_node)
 
graph.add_edge(START, "greeting_node")
graph.add_edge("greeting_node", "random_node")
 
graph.add_conditional_edges(
    "random_node",
    should_continue,
    {
        # Edge: Node
        "loop": "random_node",
        "end": END,
    },
)
 
app = graph.compile()

"looping graph"

app.invoke({"name": "Alice", "number": [], "counter": -1})

OUTPUT:
 
ENTERING LOOP 1
ENTERING LOOP 2
ENTERING LOOP 3
ENTERING LOOP 4
EXITING LOOP 5
{'name': 'Hi, there, Alice', 'number': [97, 13, 7, 70, 58], 'counter': 5}

5. Conditional Graph 7. Simple Bot Agent