ADK Workflow State Sample

Overview

This sample demonstrates different ways to manage state in an ADK Workflow. State is a dictionary shared across all nodes in the workflow execution, useful for gathering information across multiple steps without passing everything directly from one node's output to another's input.

In this sample, we show four techniques:

1. Updating state via direct dictionary mutation: ctx.state["key"] = "value"
2. Updating state by yielding an event: yield Event(state={"key": "value"})
3. Reading state via direct dictionary access: ctx.state["key"]
4. Reading state via automatic parameter injection: def func(key: str): ...

Sample Inputs

• Hello ADK!
• Testing state management.

Graph

         [ START ]
             |
             v
 [ process_initial_input ]
             |
             v
 [ update_state_via_event ]
             |
             v
  [ read_state_via_ctx ]
             |
             v
 [ read_state_via_param ]

How To

1. Update state via direct mutation: Access the context and modify ctx.state directly.

   pythonCopy

   def process_initial_input(ctx, node_input: str):
       ctx.state["original_text"] = node_input
   

2. Update state via Event: Yield an Event object with a state delta dictionary.

   pythonCopy

   def update_state_via_event(node_input: str):
       yield Event(
           state={"uppercased_text": node_input.upper()}
       )
   

3. Read state via context: Retrieve values from ctx.state.

   pythonCopy

   def read_state_via_ctx(ctx):
       original = ctx.state["original_text"]
   

4. Read state via parameter injection: Declare a function parameter that matches the key in the workflow state, and ADK will automatically populate it.

   pythonCopy

   def read_state_via_param(appended_text: str):
       return f"Final Result: {appended_text}!"