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https://github.com/google/adk-docs.git
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Polong Lin
2ccd53a3d9
* fix: update gemini 2.0 flash to latest model id for Live API * fix: use -flash for most pages instead of the live api model * fix: wording andformatting * fix: resolve merge conflict
89 lines
3.6 KiB
Python
89 lines
3.6 KiB
Python
from google.adk.agents import LlmAgent
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from google.adk.agents.callback_context import CallbackContext
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from google.adk.models import LlmResponse, LlmRequest
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from google.adk.runners import Runner
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from typing import Optional
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from google.genai import types
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from google.adk.sessions import InMemorySessionService
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GEMINI_2_FLASH="gemini-2.0-flash"
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# --- Define the Callback Function ---
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def simple_before_model_modifier(
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callback_context: CallbackContext, llm_request: LlmRequest
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) -> Optional[LlmResponse]:
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"""Inspects/modifies the LLM request or skips the call."""
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agent_name = callback_context.agent_name
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print(f"[Callback] Before model call for agent: {agent_name}")
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# Inspect the last user message in the request contents
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last_user_message = ""
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if llm_request.contents and llm_request.contents[-1].role == 'user':
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if llm_request.contents[-1].parts:
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last_user_message = llm_request.contents[-1].parts[0].text
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print(f"[Callback] Inspecting last user message: '{last_user_message}'")
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# --- Modification Example ---
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# Add a prefix to the system instruction
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original_instruction = llm_request.config.system_instruction or types.Content(role="system", parts=[])
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prefix = "[Modified by Callback] "
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# Ensure system_instruction is Content and parts list exists
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if not isinstance(original_instruction, types.Content):
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# Handle case where it might be a string (though config expects Content)
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original_instruction = types.Content(role="system", parts=[types.Part(text=str(original_instruction))])
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if not original_instruction.parts:
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original_instruction.parts.append(types.Part(text="")) # Add an empty part if none exist
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# Modify the text of the first part
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modified_text = prefix + (original_instruction.parts[0].text or "")
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original_instruction.parts[0].text = modified_text
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llm_request.config.system_instruction = original_instruction
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print(f"[Callback] Modified system instruction to: '{modified_text}'")
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# --- Skip Example ---
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# Check if the last user message contains "BLOCK"
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if "BLOCK" in last_user_message.upper():
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print("[Callback] 'BLOCK' keyword found. Skipping LLM call.")
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# Return an LlmResponse to skip the actual LLM call
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return LlmResponse(
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content=types.Content(
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role="model",
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parts=[types.Part(text="LLM call was blocked by before_model_callback.")],
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)
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)
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else:
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print("[Callback] Proceeding with LLM call.")
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# Return None to allow the (modified) request to go to the LLM
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return None
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# Create LlmAgent and Assign Callback
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my_llm_agent = LlmAgent(
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name="ModelCallbackAgent",
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model=GEMINI_2_FLASH,
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instruction="You are a helpful assistant.", # Base instruction
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description="An LLM agent demonstrating before_model_callback",
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before_model_callback=simple_before_model_modifier # Assign the function here
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)
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APP_NAME = "guardrail_app"
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USER_ID = "user_1"
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SESSION_ID = "session_001"
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# Session and Runner
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session_service = InMemorySessionService()
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session = session_service.create_session(app_name=APP_NAME, user_id=USER_ID, session_id=SESSION_ID)
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runner = Runner(agent=my_llm_agent, app_name=APP_NAME, session_service=session_service)
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# Agent Interaction
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def call_agent(query):
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content = types.Content(role='user', parts=[types.Part(text=query)])
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events = runner.run(user_id=USER_ID, session_id=SESSION_ID, new_message=content)
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for event in events:
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if event.is_final_response():
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final_response = event.content.parts[0].text
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print("Agent Response: ", final_response)
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call_agent("callback example") |