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Looping Graph

Updated
17 Sept 2026
1 min read
0 sections
Page 15 of 18
Langgraph

Objectives ✅

  1. Implement looping logic to route the flow of data to different nodes.
  2. Create a single condition edge to handle decision-making and control graph flow.
python
from typing import TypedDict, List
import random
from langgraph.graph import StateGraph, START, END

class AgentState(TypedDict):
    name: str
    number: List[int]
    counter: int
python
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"
python
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
looping graph
python
app.invoke({"name": "Alice", "number": [], "counter": -1})
powershell
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}