Class FunctionNode

src/google/adk/workflow/_function_node.py:131–525

A node that wraps a Python sync/async function or generator. Type coercions applied to function parameters (via ``TypeAdapter``): - ``dict`` → ``BaseModel`` when the annotation is a Pydantic model. - ``list[dict]`` → ``list[BaseModel]``, ``dict[K, dict]`` → ``dict[K, BaseModel]``, e

class FunctionNode(BaseNode):
  """A node that wraps a Python sync/async function or generator.

  Type coercions applied to function parameters (via ``TypeAdapter``):
    - ``dict`` → ``BaseModel`` when the annotation is a Pydantic model.
    - ``list[dict]`` → ``list[BaseModel]``, ``dict[K, dict]`` →
      ``dict[K, BaseModel]``, etc.
    - ``types.Content`` → ``str`` when the annotation expects ``str``
      (including ``Optional[str]`` / ``Union[str, ...]``).
    - All other values are validated/coerced by Pydantic's ``TypeAdapter``.
  """

  auth_config: AuthConfig | None = None
  """If set, the framework requests user authentication before running.

  When the node runs for the first time and no credential is found in
  session state, it yields an ``adk_request_credential`` event and
  interrupts.  On resume, the credential is stored and the node
  re-runs with the credential available via
  ``AuthHandler(auth_config).get_auth_response(ctx.state)``.
  """

  parameter_binding: Literal['state', 'node_input'] = 'state'
  """How function parameters are bound.

  ``'state'`` (default) binds parameters from ``ctx.state``.
  ``'node_input'`` binds parameters from ``node_input`` dict and infers
  ``input_schema`` / ``output_schema`` from the function signature
  (used when the node acts as an agent's tool).
  """

  # Private attributes (won't be serialized)
  _func: Callable[..., Any] = PrivateAttr()
  _sig: inspect.Signature = PrivateAttr()
  _type_hints: dict[str, Any] = PrivateAttr()
  _type_adapters: dict[str, TypeAdapter] = PrivateAttr()
  _context_param_name: str | None = PrivateAttr(default=None)

  def __init__(
      self,
      *,
      func: Callable[..., Any],
      name: str | None = None,
      rerun_on_resume: bool = False,
      retry_config: RetryConfig | None = None,
      timeout: float | None = None,
      auth_config: AuthConfig | None = None,
      parameter_binding: Literal['state', 'node_input'] = 'state',
      state_schema: type[BaseModel] | None = None,
  ):
    """Initializes FunctionNode.

    Args:
      func: A sync/async function or sync/async generator function that forms
        the node's logic. It can accept 'ctx: Context' and 'node_input: Any' as
        arguments, depending on its signature. If the function is not a
        generator, its return value will be wrapped in an Event, unless the
        return value is None.