@Marvin how can I most effectively use the wait for input function?

Using the

wait_for_input

function effectively in Prefect involves creating asynchronous tasks or flows and awaiting user input or other appropriate events. Below is a generic code example of an asynchronous flow that you can consider as a basis for implementing

wait_for_input

. However, note that this example does not directly use

wait_for_input

, as it's more about handling asynchronous tasks in Prefect. For more specific usage related to

wait_for_input

, you would need to create a task that awaits input inside an asynchronous flow:

python
import asyncio
from prefect import flow

async def some_async_function():
    await asyncio.sleep(1)
    return "I'm an async function"

@flow(log_prints=True)  # Sends `print` statements as INFO logs.
async def my_async_workflow():
    print("I can call any python code here, including prefect tasks or flows")
    await some_async_function()

if __name__ == "__main__":
    asyncio.run(my_async_workflow())  # Run it like a normal async Python function.
    
    # Or serve it as a long-lived process if needed.
    # my_async_workflow.serve("my-deployment-name")

Please keep in mind that this is a basic example, and the actual

wait_for_input

function should typically be implemented within a task to pause execution until a certain condition is met. You can find the full code for this basic asynchronous example here. For specific questions about the

wait_for_input

function, I would recommend consulting Prefect's documentation or codebase, as I do not have prior experience with Prefect 2.x and the function in question.

@Marvin can you also provide an example that actually uses wait_for_input?

It seems I've given you another sample that does not use

wait_for_input

. Unfortunately, I don't have a direct example for

wait_for_input

as it's not part of the default code examples provided for Prefect workflows. The

wait_for_input

function or its equivalent behavior might involve prompting the user or another system for input and pausing the flow execution until that input is received. However, to create a task in Prefect that waits for user input, you might write a task function that uses the built-in Python

input()

function to prompt the user. Please keep in mind that this approach is more suitable for local testing and debugging rather than for production deployments, especially in a distributed setup. Here's how you might create such a task:

python
from prefect import task, flow

@task
def wait_for_user_input(prompt):
    return input(prompt)

@flow
def my_flow_with_input():
    user_input = wait_for_user_input("Please enter some input: ").result()
    print(f"You entered: {user_input}")

if __name__ == "__main__":
    my_flow_with_input()

Remember, this is an illustrative example, and using

input()

within a flow is not generally recommended for automated workflows in production settings. The actual

wait_for_input

behavior would typically be achieved through event-driven tasks or other asynchronous communication mechanisms within Prefect, like waiting on an external event or message queue. Since it appears there is not a straightforward code example available, I recommend checking Prefect's documentation or forums to see if more detailed guidance on implementing

wait_for_input

functionality exists. If it is a feature or specific use case in the Prefect 2.x version, the community or developers might have further insights or code samples.

@Marvin no i think he means interactive workflows, idk if it’s documented but you can wait for a pydantic model as input. just say you can’t find it if you can’t

It seems like you're looking for guidance on creating interactive workflows in Prefect that involve waiting for a Pydantic model as input. While I don't have an exact example, the Prefect documentation does mention the ability to set up interactive workflows where you can wait for manual, at-runtime inputs through the

wait_for_input

parameter with functions like

pause_flow_run

or

suspend_flow_run

. Here's an excerpt from the documentation that explains how to use Pydantic models with these functions:

python
from prefect import flow, pause_flow_run, get_run_logger
from pydantic import BaseModel

class User(BaseModel):
    name: str
    age: int

@flow
async def greet_user():
    logger = get_run_logger()
    user = await pause_flow_run(wait_for_input=User)
    <http://logger.info|logger.info>(f"Hello, {user.name}!")

In this example, when you pass a

pydantic.BaseModel

class as the

wait_for_input

parameter, Prefect will automatically render a form with client-side validation and provide an API endpoint clients can use to submit input. For more information, you could refer to the following documentation pages: - Interactive workflows on Prefect's changelog - Creating interactive workflows in Prefect docs These sources should provide guidance on how to structure interactive workflows and wait for input using Pydantic models in Prefect.