ADK Workflow Loop Sample

Overview

This sample demonstrates how to create a feedback loop between different nodes in ADK Workflows.

It takes a user-provided topic and uses the generate_headline agent to write a headline. The evaluate_headline agent then grades the headline as either "tech-related" or "unrelated", providing feedback if it's unrelated. The route_headline function checks this grade. If the headline is "unrelated", the workflow loops back to the generate_headline agent, passing the feedback so it can try again. This process repeats until a "tech-related" headline is generated.

In ADK Workflows, loops allow for iterative refinement and evaluation by conditionally routing execution back to an earlier node in the sequence.

Sample Inputs

flower
quantum mechanics
renewable energy

Graph

text

                  [ START ]
                      |
                      v
              [ process_input ]
                      |
                      v
          +->[ generate_headline ]
          |           |
          |           v
    (feedback) [ evaluate_headline ]
          |           |
          |           v
          |   [ route_headline ]
          |        /      \
          +--"unrelated"  "tech-related"
                             |
                             v
                        (Loop ends)

How To

Define a node (like route_headline) that yields an Event with a specific route based on a condition:
python
```
def route_headline(node_input: Feedback):
  return Event(route=node_input.grade)
```
In the Workflow edges definition, create a conditional edge that connects the routing node back to a previous node in the workflow, using a routing map dict:
python
```
(route_headline, {"unrelated": generate_headline})
```
This creates the cycle. If the route yielded by route_headline is "unrelated", execution jumps back to generate_headline.