prefect.input.run_input
¶
This module contains functions that allow sending type-checked RunInput
data
to flows at runtime. Flows can send back responses, establishing two-way
channels with senders. These functions are particularly useful for systems that
require ongoing data transfer or need to react to input quickly.
real-time interaction and efficient data handling. It's designed to facilitate
dynamic communication within distributed or microservices-oriented systems,
making it ideal for scenarios requiring continuous data synchronization and
processing. It's particularly useful for systems that require ongoing data
input and output.
The following is an example of two flows. One sends a random number to the other and waits for a response. The other receives the number, squares it, and sends the result back. The sender flow then prints the result.
Sender flow:
import random
from uuid import UUID
from prefect import flow, get_run_logger
from prefect.input import RunInput
class NumberData(RunInput):
number: int
@flow
async def sender_flow(receiver_flow_run_id: UUID):
logger = get_run_logger()
the_number = random.randint(1, 100)
await NumberData(number=the_number).send_to(receiver_flow_run_id)
receiver = NumberData.receive(flow_run_id=receiver_flow_run_id)
squared = await receiver.next()
logger.info(f"{the_number} squared is {squared.number}")
Receiver flow:
import random
from uuid import UUID
from prefect import flow, get_run_logger
from prefect.input import RunInput
class NumberData(RunInput):
number: int
@flow
async def receiver_flow():
async for data in NumberData.receive():
squared = data.number ** 2
data.respond(NumberData(number=squared))
AutomaticRunInput
¶
Bases: RunInput
, Generic[T]
Source code in prefect/input/run_input.py
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load
async
classmethod
¶
Load the run input response from the given key.
Parameters:
Name | Type | Description | Default |
---|---|---|---|
- |
keyset (Keyset
|
the keyset to load the input for |
required |
- |
flow_run_id (UUID
|
the flow run ID to load the input for |
required |
Source code in prefect/input/run_input.py
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subclass_from_type
classmethod
¶
Create a new AutomaticRunInput
subclass from the given type.
This method uses the type's name as a key prefix to identify related flow run inputs. This helps in ensuring that values saved under a type (like List[int]) are retrievable under the generic type name (like "list").
Source code in prefect/input/run_input.py
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RunInput
¶
Bases: BaseModel
Source code in prefect/input/run_input.py
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load
async
classmethod
¶
Load the run input response from the given key.
Parameters:
Name | Type | Description | Default |
---|---|---|---|
- |
keyset (Keyset
|
the keyset to load the input for |
required |
- |
flow_run_id (UUID
|
the flow run ID to load the input for |
required |
Source code in prefect/input/run_input.py
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load_from_flow_run_input
classmethod
¶
Load the run input from a FlowRunInput object.
Parameters:
Name | Type | Description | Default |
---|---|---|---|
- |
flow_run_input (FlowRunInput
|
the flow run input to load the input for |
required |
Source code in prefect/input/run_input.py
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save
async
classmethod
¶
Save the run input response to the given key.
Parameters:
Name | Type | Description | Default |
---|---|---|---|
- |
keyset (Keyset
|
the keyset to save the input for |
required |
- |
flow_run_id (UUID
|
the flow run ID to save the input for |
required |
Source code in prefect/input/run_input.py
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subclass_from_base_model_type
classmethod
¶
Create a new RunInput
subclass from the given pydantic.BaseModel
subclass.
Parameters:
Name | Type | Description | Default |
---|---|---|---|
- |
model_cls (pydantic.BaseModel subclass
|
the class from which
to create the new |
required |
Source code in prefect/input/run_input.py
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with_initial_data
classmethod
¶
Create a new RunInput
subclass with the given initial data as field
defaults.
Parameters:
Name | Type | Description | Default |
---|---|---|---|
- |
description (str
|
a description to show when resuming a flow run that requires input |
required |
- |
kwargs (Any
|
the initial data to populate the subclass |
required |
Source code in prefect/input/run_input.py
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keyset_from_base_key
¶
Get the keyset for the given base key.
Parameters:
Name | Type | Description | Default |
---|---|---|---|
- |
base_key (str
|
the base key to get the keyset for |
required |
Returns:
Type | Description |
---|---|
Keyset
|
|
Source code in prefect/input/run_input.py
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keyset_from_paused_state
¶
Get the keyset for the given Paused state.
Parameters:
Name | Type | Description | Default |
---|---|---|---|
- |
state (State
|
the state to get the keyset for |
required |
Source code in prefect/input/run_input.py
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run_input_subclass_from_type
¶
Create a new RunInput
subclass from the given type.
Source code in prefect/input/run_input.py
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