Files
crewAI/src/crewai/flow/flow.py
Devin AI 29617cd228 Fix Flow initialization with Pydantic models having required fields
- Modified _create_initial_state() to accept kwargs parameter
- Pass kwargs when instantiating BaseModel classes
- Updated __init__() to pass kwargs to _create_initial_state()
- Added comprehensive tests covering various scenarios

Fixes #3744

Co-Authored-By: João <joao@crewai.com>
2025-10-20 19:50:16 +00:00

1399 lines
52 KiB
Python

import asyncio
import copy
import inspect
import logging
from collections.abc import Callable
from typing import Any, ClassVar, Generic, TypeVar, cast
from uuid import uuid4
from opentelemetry import baggage
from opentelemetry.context import attach, detach
from pydantic import BaseModel, Field, ValidationError
from crewai.events.event_bus import crewai_event_bus
from crewai.events.listeners.tracing.trace_listener import (
TraceCollectionListener,
)
from crewai.events.listeners.tracing.utils import (
is_tracing_enabled,
should_auto_collect_first_time_traces,
)
from crewai.events.types.flow_events import (
FlowCreatedEvent,
FlowFinishedEvent,
FlowPlotEvent,
FlowStartedEvent,
MethodExecutionFailedEvent,
MethodExecutionFinishedEvent,
MethodExecutionStartedEvent,
)
from crewai.flow.flow_visualizer import plot_flow
from crewai.flow.persistence.base import FlowPersistence
from crewai.flow.types import FlowExecutionData
from crewai.flow.utils import get_possible_return_constants
from crewai.utilities.printer import Printer, PrinterColor
logger = logging.getLogger(__name__)
class FlowState(BaseModel):
"""Base model for all flow states, ensuring each state has a unique ID."""
id: str = Field(
default_factory=lambda: str(uuid4()),
description="Unique identifier for the flow state",
)
# type variables with explicit bounds
T = TypeVar("T", bound=dict[str, Any] | BaseModel) # Generic flow state type parameter
StateT = TypeVar(
"StateT", bound=dict[str, Any] | BaseModel
) # State validation type parameter
def ensure_state_type(state: Any, expected_type: type[StateT]) -> StateT:
"""Ensure state matches expected type with proper validation.
Args:
state: State instance to validate
expected_type: Expected type for the state
Returns:
Validated state instance
Raises:
TypeError: If state doesn't match expected type
ValueError: If state validation fails
"""
"""Ensure state matches expected type with proper validation.
Args:
state: State instance to validate
expected_type: Expected type for the state
Returns:
Validated state instance
Raises:
TypeError: If state doesn't match expected type
ValueError: If state validation fails
"""
if expected_type is dict:
if not isinstance(state, dict):
raise TypeError(f"Expected dict, got {type(state).__name__}")
return cast(StateT, state)
if isinstance(expected_type, type) and issubclass(expected_type, BaseModel):
if not isinstance(state, expected_type):
raise TypeError(
f"Expected {expected_type.__name__}, got {type(state).__name__}"
)
return cast(StateT, state)
raise TypeError(f"Invalid expected_type: {expected_type}")
def start(condition: str | dict | Callable | None = None) -> Callable:
"""
Marks a method as a flow's starting point.
This decorator designates a method as an entry point for the flow execution.
It can optionally specify conditions that trigger the start based on other
method executions.
Parameters
----------
condition : Optional[Union[str, dict, Callable]], optional
Defines when the start method should execute. Can be:
- str: Name of a method that triggers this start
- dict: Result from or_() or and_(), including nested conditions
- Callable: A method reference that triggers this start
Default is None, meaning unconditional start.
Returns
-------
Callable
A decorator function that marks the method as a flow start point.
Raises
------
ValueError
If the condition format is invalid.
Examples
--------
>>> @start() # Unconditional start
>>> def begin_flow(self):
... pass
>>> @start("method_name") # Start after specific method
>>> def conditional_start(self):
... pass
>>> @start(and_("method1", "method2")) # Start after multiple methods
>>> def complex_start(self):
... pass
"""
def decorator(func):
func.__is_start_method__ = True
if condition is not None:
if isinstance(condition, str):
func.__trigger_methods__ = [condition]
func.__condition_type__ = "OR"
elif isinstance(condition, dict) and "type" in condition:
if "conditions" in condition:
func.__trigger_condition__ = condition
func.__trigger_methods__ = _extract_all_methods(condition)
func.__condition_type__ = condition["type"]
elif "methods" in condition:
func.__trigger_methods__ = condition["methods"]
func.__condition_type__ = condition["type"]
else:
raise ValueError(
"Condition dict must contain 'conditions' or 'methods'"
)
elif callable(condition) and hasattr(condition, "__name__"):
func.__trigger_methods__ = [condition.__name__]
func.__condition_type__ = "OR"
else:
raise ValueError(
"Condition must be a method, string, or a result of or_() or and_()"
)
return func
return decorator
def listen(condition: str | dict | Callable) -> Callable:
"""
Creates a listener that executes when specified conditions are met.
This decorator sets up a method to execute in response to other method
executions in the flow. It supports both simple and complex triggering
conditions.
Parameters
----------
condition : Union[str, dict, Callable]
Specifies when the listener should execute. Can be:
- str: Name of a method that triggers this listener
- dict: Result from or_() or and_(), including nested conditions
- Callable: A method reference that triggers this listener
Returns
-------
Callable
A decorator function that sets up the method as a listener.
Raises
------
ValueError
If the condition format is invalid.
Examples
--------
>>> @listen("process_data") # Listen to single method
>>> def handle_processed_data(self):
... pass
>>> @listen(or_("success", "failure")) # Listen to multiple methods
>>> def handle_completion(self):
... pass
"""
def decorator(func):
if isinstance(condition, str):
func.__trigger_methods__ = [condition]
func.__condition_type__ = "OR"
elif isinstance(condition, dict) and "type" in condition:
if "conditions" in condition:
func.__trigger_condition__ = condition
func.__trigger_methods__ = _extract_all_methods(condition)
func.__condition_type__ = condition["type"]
elif "methods" in condition:
func.__trigger_methods__ = condition["methods"]
func.__condition_type__ = condition["type"]
else:
raise ValueError(
"Condition dict must contain 'conditions' or 'methods'"
)
elif callable(condition) and hasattr(condition, "__name__"):
func.__trigger_methods__ = [condition.__name__]
func.__condition_type__ = "OR"
else:
raise ValueError(
"Condition must be a method, string, or a result of or_() or and_()"
)
return func
return decorator
def router(condition: str | dict | Callable) -> Callable:
"""
Creates a routing method that directs flow execution based on conditions.
This decorator marks a method as a router, which can dynamically determine
the next steps in the flow based on its return value. Routers are triggered
by specified conditions and can return constants that determine which path
the flow should take.
Parameters
----------
condition : Union[str, dict, Callable]
Specifies when the router should execute. Can be:
- str: Name of a method that triggers this router
- dict: Result from or_() or and_(), including nested conditions
- Callable: A method reference that triggers this router
Returns
-------
Callable
A decorator function that sets up the method as a router.
Raises
------
ValueError
If the condition format is invalid.
Examples
--------
>>> @router("check_status")
>>> def route_based_on_status(self):
... if self.state.status == "success":
... return SUCCESS
... return FAILURE
>>> @router(and_("validate", "process"))
>>> def complex_routing(self):
... if all([self.state.valid, self.state.processed]):
... return CONTINUE
... return STOP
"""
def decorator(func):
func.__is_router__ = True
if isinstance(condition, str):
func.__trigger_methods__ = [condition]
func.__condition_type__ = "OR"
elif isinstance(condition, dict) and "type" in condition:
if "conditions" in condition:
func.__trigger_condition__ = condition
func.__trigger_methods__ = _extract_all_methods(condition)
func.__condition_type__ = condition["type"]
elif "methods" in condition:
func.__trigger_methods__ = condition["methods"]
func.__condition_type__ = condition["type"]
else:
raise ValueError(
"Condition dict must contain 'conditions' or 'methods'"
)
elif callable(condition) and hasattr(condition, "__name__"):
func.__trigger_methods__ = [condition.__name__]
func.__condition_type__ = "OR"
else:
raise ValueError(
"Condition must be a method, string, or a result of or_() or and_()"
)
return func
return decorator
def or_(*conditions: str | dict | Callable) -> dict:
"""
Combines multiple conditions with OR logic for flow control.
Creates a condition that is satisfied when any of the specified conditions
are met. This is used with @start, @listen, or @router decorators to create
complex triggering conditions.
Parameters
----------
*conditions : Union[str, dict, Callable]
Variable number of conditions that can be:
- str: Method names
- dict: Existing condition dictionaries (nested conditions)
- Callable: Method references
Returns
-------
dict
A condition dictionary with format:
{"type": "OR", "conditions": list_of_conditions}
where each condition can be a string (method name) or a nested dict
Raises
------
ValueError
If any condition is invalid.
Examples
--------
>>> @listen(or_("success", "timeout"))
>>> def handle_completion(self):
... pass
>>> @listen(or_(and_("step1", "step2"), "step3"))
>>> def handle_nested(self):
... pass
"""
processed_conditions: list[str | dict[str, Any]] = []
for condition in conditions:
if isinstance(condition, dict):
processed_conditions.append(condition)
elif isinstance(condition, str):
processed_conditions.append(condition)
elif callable(condition):
processed_conditions.append(getattr(condition, "__name__", repr(condition)))
else:
raise ValueError("Invalid condition in or_()")
return {"type": "OR", "conditions": processed_conditions}
def and_(*conditions: str | dict | Callable) -> dict:
"""
Combines multiple conditions with AND logic for flow control.
Creates a condition that is satisfied only when all specified conditions
are met. This is used with @start, @listen, or @router decorators to create
complex triggering conditions.
Parameters
----------
*conditions : Union[str, dict, Callable]
Variable number of conditions that can be:
- str: Method names
- dict: Existing condition dictionaries (nested conditions)
- Callable: Method references
Returns
-------
dict
A condition dictionary with format:
{"type": "AND", "conditions": list_of_conditions}
where each condition can be a string (method name) or a nested dict
Raises
------
ValueError
If any condition is invalid.
Examples
--------
>>> @listen(and_("validated", "processed"))
>>> def handle_complete_data(self):
... pass
>>> @listen(and_(or_("step1", "step2"), "step3"))
>>> def handle_nested(self):
... pass
"""
processed_conditions: list[str | dict[str, Any]] = []
for condition in conditions:
if isinstance(condition, dict):
processed_conditions.append(condition)
elif isinstance(condition, str):
processed_conditions.append(condition)
elif callable(condition):
processed_conditions.append(getattr(condition, "__name__", repr(condition)))
else:
raise ValueError("Invalid condition in and_()")
return {"type": "AND", "conditions": processed_conditions}
def _normalize_condition(condition: str | dict | list) -> dict:
"""Normalize a condition to standard format with 'conditions' key.
Args:
condition: Can be a string (method name), dict (condition), or list
Returns:
Normalized dict with 'type' and 'conditions' keys
"""
if isinstance(condition, str):
return {"type": "OR", "conditions": [condition]}
if isinstance(condition, dict):
if "conditions" in condition:
return condition
if "methods" in condition:
return {"type": condition["type"], "conditions": condition["methods"]}
return condition
if isinstance(condition, list):
return {"type": "OR", "conditions": condition}
return {"type": "OR", "conditions": [condition]}
def _extract_all_methods(condition: str | dict | list) -> list[str]:
"""Extract all method names from a condition (including nested).
Args:
condition: Can be a string, dict, or list
Returns:
List of all method names in the condition tree
"""
if isinstance(condition, str):
return [condition]
if isinstance(condition, dict):
normalized = _normalize_condition(condition)
methods = []
for sub_cond in normalized.get("conditions", []):
methods.extend(_extract_all_methods(sub_cond))
return methods
if isinstance(condition, list):
methods = []
for item in condition:
methods.extend(_extract_all_methods(item))
return methods
return []
class FlowMeta(type):
def __new__(mcs, name, bases, dct):
cls = super().__new__(mcs, name, bases, dct)
start_methods = []
listeners = {}
router_paths = {}
routers = set()
for attr_name, attr_value in dct.items():
# Check for any flow-related attributes
if (
hasattr(attr_value, "__is_flow_method__")
or hasattr(attr_value, "__is_start_method__")
or hasattr(attr_value, "__trigger_methods__")
or hasattr(attr_value, "__is_router__")
):
# Register start methods
if hasattr(attr_value, "__is_start_method__"):
start_methods.append(attr_name)
# Register listeners and routers
if hasattr(attr_value, "__trigger_methods__"):
methods = attr_value.__trigger_methods__
condition_type = getattr(attr_value, "__condition_type__", "OR")
if hasattr(attr_value, "__trigger_condition__"):
listeners[attr_name] = attr_value.__trigger_condition__
else:
listeners[attr_name] = (condition_type, methods)
if (
hasattr(attr_value, "__is_router__")
and attr_value.__is_router__
):
routers.add(attr_name)
possible_returns = get_possible_return_constants(attr_value)
if possible_returns:
router_paths[attr_name] = possible_returns
cls._start_methods = start_methods
cls._listeners = listeners
cls._routers = routers
cls._router_paths = router_paths
return cls
class Flow(Generic[T], metaclass=FlowMeta):
"""Base class for all flows.
type parameter T must be either dict[str, Any] or a subclass of BaseModel."""
_printer = Printer()
_start_methods: ClassVar[list[str]] = []
_listeners: ClassVar[dict[str, tuple[str, list[str]]]] = {}
_routers: ClassVar[set[str]] = set()
_router_paths: ClassVar[dict[str, list[str]]] = {}
initial_state: type[T] | T | None = None
name: str | None = None
tracing: bool | None = False
def __class_getitem__(cls: type["Flow"], item: type[T]) -> type["Flow"]:
class _FlowGeneric(cls): # type: ignore
_initial_state_t = item # type: ignore
_FlowGeneric.__name__ = f"{cls.__name__}[{item.__name__}]"
return _FlowGeneric
def __init__(
self,
persistence: FlowPersistence | None = None,
tracing: bool | None = False,
**kwargs: Any,
) -> None:
"""Initialize a new Flow instance.
Args:
persistence: Optional persistence backend for storing flow states
**kwargs: Additional state values to initialize or override
"""
# Initialize basic instance attributes
self._methods: dict[str, Callable] = {}
self._method_execution_counts: dict[str, int] = {}
self._pending_and_listeners: dict[str, set[str]] = {}
self._method_outputs: list[Any] = [] # list to store all method outputs
self._completed_methods: set[str] = set() # Track completed methods for reload
self._persistence: FlowPersistence | None = persistence
self._is_execution_resuming: bool = False
# Initialize state with initial values and kwargs
self._state = self._create_initial_state(kwargs if kwargs else None)
self.tracing = tracing
if (
is_tracing_enabled()
or self.tracing
or should_auto_collect_first_time_traces()
):
trace_listener = TraceCollectionListener()
trace_listener.setup_listeners(crewai_event_bus)
crewai_event_bus.emit(
self,
FlowCreatedEvent(
type="flow_created",
flow_name=self.name or self.__class__.__name__,
),
)
# Register all flow-related methods
for method_name in dir(self):
if not method_name.startswith("_"):
method = getattr(self, method_name)
# Check for any flow-related attributes
if (
hasattr(method, "__is_flow_method__")
or hasattr(method, "__is_start_method__")
or hasattr(method, "__trigger_methods__")
or hasattr(method, "__is_router__")
):
# Ensure method is bound to this instance
if not hasattr(method, "__self__"):
method = method.__get__(self, self.__class__)
self._methods[method_name] = method
def _create_initial_state(self, kwargs: dict[str, Any] | None = None) -> T:
"""Create and initialize flow state with UUID and default values.
Args:
kwargs: Optional dictionary of initial state values
Returns:
New state instance with UUID and default values initialized
Raises:
ValueError: If structured state model lacks 'id' field
TypeError: If state is neither BaseModel nor dictionary
"""
if kwargs is None:
kwargs = {}
# Handle case where initial_state is None but we have a type parameter
if self.initial_state is None and hasattr(self, "_initial_state_t"):
state_type = self._initial_state_t
if isinstance(state_type, type):
if issubclass(state_type, FlowState):
# Create instance with kwargs
instance = state_type(**kwargs)
if not hasattr(instance, "id"):
instance.id = str(uuid4())
return cast(T, instance)
if issubclass(state_type, BaseModel):
# Create a new type that includes the ID field
class StateWithId(state_type, FlowState): # type: ignore
pass
instance = StateWithId(**kwargs)
if not hasattr(instance, "id"):
instance.id = str(uuid4())
return cast(T, instance)
if state_type is dict:
state_dict = {"id": str(uuid4())}
state_dict.update(kwargs)
return cast(T, state_dict)
# Handle case where no initial state is provided
if self.initial_state is None:
state_dict = {"id": str(uuid4())}
state_dict.update(kwargs)
return cast(T, state_dict)
# Handle case where initial_state is a type (class)
if isinstance(self.initial_state, type):
if issubclass(self.initial_state, FlowState):
return cast(T, self.initial_state(**kwargs)) # Uses model defaults and kwargs
if issubclass(self.initial_state, BaseModel):
# Validate that the model has an id field
model_fields = getattr(self.initial_state, "model_fields", None)
if not model_fields or "id" not in model_fields:
raise ValueError("Flow state model must have an 'id' field")
return cast(T, self.initial_state(**kwargs)) # Uses model defaults and kwargs
if self.initial_state is dict:
state_dict = {"id": str(uuid4())}
state_dict.update(kwargs)
return cast(T, state_dict)
# Handle dictionary instance case
if isinstance(self.initial_state, dict):
new_state = dict(self.initial_state) # Copy to avoid mutations
if "id" not in new_state:
new_state["id"] = str(uuid4())
new_state.update(kwargs) # Apply kwargs
return cast(T, new_state)
# Handle BaseModel instance case
if isinstance(self.initial_state, BaseModel):
model = cast(BaseModel, self.initial_state)
if not hasattr(model, "id"):
raise ValueError("Flow state model must have an 'id' field")
# Create new instance with same values to avoid mutations
if hasattr(model, "model_dump"):
# Pydantic v2
state_dict = model.model_dump()
elif hasattr(model, "dict"):
# Pydantic v1
state_dict = model.dict()
else:
# Fallback for other BaseModel implementations
state_dict = {
k: v for k, v in model.__dict__.items() if not k.startswith("_")
}
state_dict.update(kwargs)
# Create new instance of the same class
model_class = type(model)
return cast(T, model_class(**state_dict))
raise TypeError(
f"Initial state must be dict or BaseModel, got {type(self.initial_state)}"
)
def _copy_state(self) -> T:
return copy.deepcopy(self._state)
@property
def state(self) -> T:
return self._state
@property
def method_outputs(self) -> list[Any]:
"""Returns the list of all outputs from executed methods."""
return self._method_outputs
@property
def flow_id(self) -> str:
"""Returns the unique identifier of this flow instance.
This property provides a consistent way to access the flow's unique identifier
regardless of the underlying state implementation (dict or BaseModel).
Returns:
str: The flow's unique identifier, or an empty string if not found
Note:
This property safely handles both dictionary and BaseModel state types,
returning an empty string if the ID cannot be retrieved rather than raising
an exception.
Example:
```python
flow = MyFlow()
print(f"Current flow ID: {flow.flow_id}") # Safely get flow ID
```
"""
try:
if not hasattr(self, "_state"):
return ""
if isinstance(self._state, dict):
return str(self._state.get("id", ""))
if isinstance(self._state, BaseModel):
return str(getattr(self._state, "id", ""))
return ""
except (AttributeError, TypeError):
return "" # Safely handle any unexpected attribute access issues
def _initialize_state(self, inputs: dict[str, Any]) -> None:
"""Initialize or update flow state with new inputs.
Args:
inputs: Dictionary of state values to set/update
Raises:
ValueError: If validation fails for structured state
TypeError: If state is neither BaseModel nor dictionary
"""
if isinstance(self._state, dict):
# For dict states, preserve existing fields unless overridden
current_id = self._state.get("id")
# Only update specified fields
for k, v in inputs.items():
self._state[k] = v
# Ensure ID is preserved or generated
if current_id:
self._state["id"] = current_id
elif "id" not in self._state:
self._state["id"] = str(uuid4())
elif isinstance(self._state, BaseModel):
# For BaseModel states, preserve existing fields unless overridden
try:
model = cast(BaseModel, self._state)
# Get current state as dict
if hasattr(model, "model_dump"):
current_state = model.model_dump()
elif hasattr(model, "dict"):
current_state = model.dict()
else:
current_state = {
k: v for k, v in model.__dict__.items() if not k.startswith("_")
}
# Create new state with preserved fields and updates
new_state = {**current_state, **inputs}
# Create new instance with merged state
model_class = type(model)
if hasattr(model_class, "model_validate"):
# Pydantic v2
self._state = cast(T, model_class.model_validate(new_state))
elif hasattr(model_class, "parse_obj"):
# Pydantic v1
self._state = cast(T, model_class.parse_obj(new_state))
else:
# Fallback for other BaseModel implementations
self._state = cast(T, model_class(**new_state))
except ValidationError as e:
raise ValueError(f"Invalid inputs for structured state: {e}") from e
else:
raise TypeError("State must be a BaseModel instance or a dictionary.")
def _restore_state(self, stored_state: dict[str, Any]) -> None:
"""Restore flow state from persistence.
Args:
stored_state: Previously stored state to restore
Raises:
ValueError: If validation fails for structured state
TypeError: If state is neither BaseModel nor dictionary
"""
# When restoring from persistence, use the stored ID
stored_id = stored_state.get("id")
if not stored_id:
raise ValueError("Stored state must have an 'id' field")
if isinstance(self._state, dict):
# For dict states, update all fields from stored state
self._state.clear()
self._state.update(stored_state)
elif isinstance(self._state, BaseModel):
# For BaseModel states, create new instance with stored values
model = cast(BaseModel, self._state)
if hasattr(model, "model_validate"):
# Pydantic v2
self._state = cast(T, type(model).model_validate(stored_state))
elif hasattr(model, "parse_obj"):
# Pydantic v1
self._state = cast(T, type(model).parse_obj(stored_state))
else:
# Fallback for other BaseModel implementations
self._state = cast(T, type(model)(**stored_state))
else:
raise TypeError(f"State must be dict or BaseModel, got {type(self._state)}")
def reload(self, execution_data: FlowExecutionData) -> None:
"""Reloads the flow from an execution data dict.
This method restores the flow's execution ID, completed methods, and state,
allowing it to resume from where it left off.
Args:
execution_data: Flow execution data containing:
- id: Flow execution ID
- flow: Flow structure
- completed_methods: list of successfully completed methods
- execution_methods: All execution methods with their status
"""
flow_id = execution_data.get("id")
if flow_id:
self._update_state_field("id", flow_id)
self._completed_methods = {
name
for method_data in execution_data.get("completed_methods", [])
if (name := method_data.get("flow_method", {}).get("name")) is not None
}
execution_methods = execution_data.get("execution_methods", [])
if not execution_methods:
return
sorted_methods = sorted(
execution_methods,
key=lambda m: m.get("started_at", ""),
)
state_to_apply = None
for method in reversed(sorted_methods):
if method.get("final_state"):
state_to_apply = method["final_state"]
break
if not state_to_apply and sorted_methods:
last_method = sorted_methods[-1]
if last_method.get("initial_state"):
state_to_apply = last_method["initial_state"]
if state_to_apply:
self._apply_state_updates(state_to_apply)
for method in sorted_methods[:-1]:
method_name = method.get("flow_method", {}).get("name")
if method_name:
self._completed_methods.add(method_name)
def _update_state_field(self, field_name: str, value: Any) -> None:
"""Update a single field in the state."""
if isinstance(self._state, dict):
self._state[field_name] = value
elif hasattr(self._state, field_name):
object.__setattr__(self._state, field_name, value)
def _apply_state_updates(self, updates: dict[str, Any]) -> None:
"""Apply multiple state updates efficiently."""
if isinstance(self._state, dict):
self._state.update(updates)
elif hasattr(self._state, "__dict__"):
for key, value in updates.items():
if hasattr(self._state, key):
object.__setattr__(self._state, key, value)
def kickoff(self, inputs: dict[str, Any] | None = None) -> Any:
"""
Start the flow execution in a synchronous context.
This method wraps kickoff_async so that all state initialization and event
emission is handled in the asynchronous method.
"""
async def run_flow():
return await self.kickoff_async(inputs)
return asyncio.run(run_flow())
async def kickoff_async(self, inputs: dict[str, Any] | None = None) -> Any:
"""
Start the flow execution asynchronously.
This method performs state restoration (if an 'id' is provided and persistence is available)
and updates the flow state with any additional inputs. It then emits the FlowStartedEvent,
logs the flow startup, and executes all start methods. Once completed, it emits the
FlowFinishedEvent and returns the final output.
Args:
inputs: Optional dictionary containing input values and/or a state ID for restoration.
Returns:
The final output from the flow, which is the result of the last executed method.
"""
ctx = baggage.set_baggage("flow_inputs", inputs or {})
flow_token = attach(ctx)
try:
# Reset flow state for fresh execution unless restoring from persistence
is_restoring = inputs and "id" in inputs and self._persistence is not None
if not is_restoring:
# Clear completed methods and outputs for a fresh start
self._completed_methods.clear()
self._method_outputs.clear()
self._pending_and_listeners.clear()
else:
# We're restoring from persistence, set the flag
self._is_execution_resuming = True
if inputs:
# Override the id in the state if it exists in inputs
if "id" in inputs:
if isinstance(self._state, dict):
self._state["id"] = inputs["id"]
elif isinstance(self._state, BaseModel):
setattr(self._state, "id", inputs["id"]) # noqa: B010
# If persistence is enabled, attempt to restore the stored state using the provided id.
if "id" in inputs and self._persistence is not None:
restore_uuid = inputs["id"]
stored_state = self._persistence.load_state(restore_uuid)
if stored_state:
self._log_flow_event(
f"Loading flow state from memory for UUID: {restore_uuid}",
color="yellow",
)
self._restore_state(stored_state)
else:
self._log_flow_event(
f"No flow state found for UUID: {restore_uuid}", color="red"
)
# Update state with any additional inputs (ignoring the 'id' key)
filtered_inputs = {k: v for k, v in inputs.items() if k != "id"}
if filtered_inputs:
self._initialize_state(filtered_inputs)
# Emit FlowStartedEvent and log the start of the flow.
crewai_event_bus.emit(
self,
FlowStartedEvent(
type="flow_started",
flow_name=self.name or self.__class__.__name__,
inputs=inputs,
),
)
self._log_flow_event(
f"Flow started with ID: {self.flow_id}", color="bold_magenta"
)
if inputs is not None and "id" not in inputs:
self._initialize_state(inputs)
tasks = [
self._execute_start_method(start_method)
for start_method in self._start_methods
]
await asyncio.gather(*tasks)
# Clear the resumption flag after initial execution completes
self._is_execution_resuming = False
final_output = self._method_outputs[-1] if self._method_outputs else None
crewai_event_bus.emit(
self,
FlowFinishedEvent(
type="flow_finished",
flow_name=self.name or self.__class__.__name__,
result=final_output,
),
)
return final_output
finally:
detach(flow_token)
async def _execute_start_method(self, start_method_name: str) -> None:
"""
Executes a flow's start method and its triggered listeners.
This internal method handles the execution of methods marked with @start
decorator and manages the subsequent chain of listener executions.
Parameters
----------
start_method_name : str
The name of the start method to execute.
Notes
-----
- Executes the start method and captures its result
- Triggers execution of any listeners waiting on this start method
- Part of the flow's initialization sequence
- Skips execution if method was already completed (e.g., after reload)
- Automatically injects crewai_trigger_payload if available in flow inputs
"""
if start_method_name in self._completed_methods:
if self._is_execution_resuming:
# During resumption, skip execution but continue listeners
last_output = self._method_outputs[-1] if self._method_outputs else None
await self._execute_listeners(start_method_name, last_output)
return
# For cyclic flows, clear from completed to allow re-execution
self._completed_methods.discard(start_method_name)
method = self._methods[start_method_name]
enhanced_method = self._inject_trigger_payload_for_start_method(method)
result = await self._execute_method(start_method_name, enhanced_method)
await self._execute_listeners(start_method_name, result)
def _inject_trigger_payload_for_start_method(
self, original_method: Callable
) -> Callable:
def prepare_kwargs(*args, **kwargs):
inputs = baggage.get_baggage("flow_inputs") or {}
trigger_payload = inputs.get("crewai_trigger_payload")
sig = inspect.signature(original_method)
accepts_trigger_payload = "crewai_trigger_payload" in sig.parameters
if trigger_payload is not None and accepts_trigger_payload:
kwargs["crewai_trigger_payload"] = trigger_payload
elif trigger_payload is not None:
self._log_flow_event(
f"Trigger payload available but {original_method.__name__} doesn't accept crewai_trigger_payload parameter",
color="yellow",
)
return args, kwargs
if asyncio.iscoroutinefunction(original_method):
async def enhanced_method(*args, **kwargs):
args, kwargs = prepare_kwargs(*args, **kwargs)
return await original_method(*args, **kwargs)
else:
def enhanced_method(*args, **kwargs):
args, kwargs = prepare_kwargs(*args, **kwargs)
return original_method(*args, **kwargs)
enhanced_method.__name__ = original_method.__name__
enhanced_method.__doc__ = original_method.__doc__
return enhanced_method
async def _execute_method(
self, method_name: str, method: Callable, *args: Any, **kwargs: Any
) -> Any:
try:
dumped_params = {f"_{i}": arg for i, arg in enumerate(args)} | (
kwargs or {}
)
crewai_event_bus.emit(
self,
MethodExecutionStartedEvent(
type="method_execution_started",
method_name=method_name,
flow_name=self.name or self.__class__.__name__,
params=dumped_params,
state=self._copy_state(),
),
)
result = (
await method(*args, **kwargs)
if asyncio.iscoroutinefunction(method)
else method(*args, **kwargs)
)
self._method_outputs.append(result)
self._method_execution_counts[method_name] = (
self._method_execution_counts.get(method_name, 0) + 1
)
self._completed_methods.add(method_name)
crewai_event_bus.emit(
self,
MethodExecutionFinishedEvent(
type="method_execution_finished",
method_name=method_name,
flow_name=self.name or self.__class__.__name__,
state=self._copy_state(),
result=result,
),
)
return result
except Exception as e:
crewai_event_bus.emit(
self,
MethodExecutionFailedEvent(
type="method_execution_failed",
method_name=method_name,
flow_name=self.name or self.__class__.__name__,
error=e,
),
)
raise e
async def _execute_listeners(self, trigger_method: str, result: Any) -> None:
"""
Executes all listeners and routers triggered by a method completion.
This internal method manages the execution flow by:
1. First executing all triggered routers sequentially
2. Then executing all triggered listeners in parallel
Parameters
----------
trigger_method : str
The name of the method that triggered these listeners.
result : Any
The result from the triggering method, passed to listeners
that accept parameters.
Notes
-----
- Routers are executed sequentially to maintain flow control
- Each router's result becomes a new trigger_method
- Normal listeners are executed in parallel for efficiency
- Listeners can receive the trigger method's result as a parameter
"""
# First, handle routers repeatedly until no router triggers anymore
router_results = []
current_trigger = trigger_method
while True:
routers_triggered = self._find_triggered_methods(
current_trigger, router_only=True
)
if not routers_triggered:
break
for router_name in routers_triggered:
await self._execute_single_listener(router_name, result)
# After executing router, the router's result is the path
router_result = (
self._method_outputs[-1] if self._method_outputs else None
)
if router_result: # Only add non-None results
router_results.append(router_result)
current_trigger = (
str(router_result)
if router_result is not None
else "" # Update for next iteration of router chain
)
# Now execute normal listeners for all router results and the original trigger
all_triggers = [trigger_method, *router_results]
for current_trigger in all_triggers:
if current_trigger: # Skip None results
listeners_triggered = self._find_triggered_methods(
current_trigger, router_only=False
)
if listeners_triggered:
tasks = [
self._execute_single_listener(listener_name, result)
for listener_name in listeners_triggered
]
await asyncio.gather(*tasks)
if current_trigger in router_results:
# Find start methods triggered by this router result
for method_name in self._start_methods:
# Check if this start method is triggered by the current trigger
if method_name in self._listeners:
condition_data = self._listeners[method_name]
should_trigger = False
if isinstance(condition_data, tuple):
_, trigger_methods = condition_data
should_trigger = current_trigger in trigger_methods
elif isinstance(condition_data, dict):
all_methods = _extract_all_methods(condition_data)
should_trigger = current_trigger in all_methods
if should_trigger:
# Only execute if this is a cycle (method was already completed)
if method_name in self._completed_methods:
# For router-triggered start methods in cycles, temporarily clear resumption flag
# to allow cyclic execution
was_resuming = self._is_execution_resuming
self._is_execution_resuming = False
await self._execute_start_method(method_name)
self._is_execution_resuming = was_resuming
def _evaluate_condition(
self, condition: str | dict, trigger_method: str, listener_name: str
) -> bool:
"""Recursively evaluate a condition (simple or nested).
Args:
condition: Can be a string (method name) or dict (nested condition)
trigger_method: The method that just completed
listener_name: Name of the listener being evaluated
Returns:
True if the condition is satisfied, False otherwise
"""
if isinstance(condition, str):
return condition == trigger_method
if isinstance(condition, dict):
normalized = _normalize_condition(condition)
cond_type = normalized.get("type", "OR")
sub_conditions = normalized.get("conditions", [])
if cond_type == "OR":
return any(
self._evaluate_condition(sub_cond, trigger_method, listener_name)
for sub_cond in sub_conditions
)
if cond_type == "AND":
pending_key = f"{listener_name}:{id(condition)}"
if pending_key not in self._pending_and_listeners:
all_methods = set(_extract_all_methods(condition))
self._pending_and_listeners[pending_key] = all_methods
if trigger_method in self._pending_and_listeners[pending_key]:
self._pending_and_listeners[pending_key].discard(trigger_method)
if not self._pending_and_listeners[pending_key]:
self._pending_and_listeners.pop(pending_key, None)
return True
return False
return False
def _find_triggered_methods(
self, trigger_method: str, router_only: bool
) -> list[str]:
"""
Finds all methods that should be triggered based on conditions.
This internal method evaluates both OR and AND conditions to determine
which methods should be executed next in the flow. Supports nested conditions.
Parameters
----------
trigger_method : str
The name of the method that just completed execution.
router_only : bool
If True, only consider router methods.
If False, only consider non-router methods.
Returns
-------
list[str]
Names of methods that should be triggered.
Notes
-----
- Handles both OR and AND conditions, including nested combinations
- Maintains state for AND conditions using _pending_and_listeners
- Separates router and normal listener evaluation
"""
triggered = []
for listener_name, condition_data in self._listeners.items():
is_router = listener_name in self._routers
if router_only != is_router:
continue
if not router_only and listener_name in self._start_methods:
continue
if isinstance(condition_data, tuple):
condition_type, methods = condition_data
if condition_type == "OR":
if trigger_method in methods:
triggered.append(listener_name)
elif condition_type == "AND":
if listener_name not in self._pending_and_listeners:
self._pending_and_listeners[listener_name] = set(methods)
if trigger_method in self._pending_and_listeners[listener_name]:
self._pending_and_listeners[listener_name].discard(
trigger_method
)
if not self._pending_and_listeners[listener_name]:
triggered.append(listener_name)
self._pending_and_listeners.pop(listener_name, None)
elif isinstance(condition_data, dict):
if self._evaluate_condition(
condition_data, trigger_method, listener_name
):
triggered.append(listener_name)
return triggered
async def _execute_single_listener(self, listener_name: str, result: Any) -> None:
"""
Executes a single listener method with proper event handling.
This internal method manages the execution of an individual listener,
including parameter inspection, event emission, and error handling.
Parameters
----------
listener_name : str
The name of the listener method to execute.
result : Any
The result from the triggering method, which may be passed
to the listener if it accepts parameters.
Notes
-----
- Inspects method signature to determine if it accepts the trigger result
- Emits events for method execution start and finish
- Handles errors gracefully with detailed logging
- Recursively triggers listeners of this listener
- Supports both parameterized and parameter-less listeners
- Skips execution if method was already completed (e.g., after reload)
Error Handling
-------------
Catches and logs any exceptions during execution, preventing
individual listener failures from breaking the entire flow.
"""
if listener_name in self._completed_methods:
if self._is_execution_resuming:
# During resumption, skip execution but continue listeners
await self._execute_listeners(listener_name, None)
return
# For cyclic flows, clear from completed to allow re-execution
self._completed_methods.discard(listener_name)
try:
method = self._methods[listener_name]
sig = inspect.signature(method)
params = list(sig.parameters.values())
method_params = [p for p in params if p.name != "self"]
if method_params:
listener_result = await self._execute_method(
listener_name, method, result
)
else:
listener_result = await self._execute_method(listener_name, method)
# Execute listeners (and possibly routers) of this listener
await self._execute_listeners(listener_name, listener_result)
except Exception as e:
logger.error(f"Error executing listener {listener_name}: {e}")
raise
def _log_flow_event(
self, message: str, color: PrinterColor | None = "yellow", level: str = "info"
) -> None:
"""Centralized logging method for flow events.
This method provides a consistent interface for logging flow-related events,
combining both console output with colors and proper logging levels.
Args:
message: The message to log
color: Color to use for console output (default: yellow)
Available colors: purple, red, bold_green, bold_purple,
bold_blue, yellow, yellow
level: Log level to use (default: info)
Supported levels: info, warning
Note:
This method uses the Printer utility for colored console output
and the standard logging module for log level support.
"""
self._printer.print(message, color=color)
if level == "info":
logger.info(message)
elif level == "warning":
logger.warning(message)
def plot(self, filename: str = "crewai_flow") -> None:
crewai_event_bus.emit(
self,
FlowPlotEvent(
type="flow_plot",
flow_name=self.name or self.__class__.__name__,
),
)
plot_flow(self, filename)