@Marvin how to check if a task or flow return state failed

request = request_token.submit()

In Prefect, you can check the state of a task or flow using the

.state

attribute. For example, if you have a task or flow named

request

, you can check its state as follows:

request_state = request.state

The

request_state

will contain the state of the task or flow. If the task or flow failed,

request_state

will be an instance of the

Failed

state. You can check if the task or flow failed by comparing

request_state

to `Failed`:

from prefect.engine.state import Failed

if isinstance(request_state, Failed):
    print("The task or flow failed.")
else:
    print("The task or flow did not fail.")

In your case, if

request_token.submit()

is a task or flow, you can check if it failed as follows:

request = request_token.submit()
if isinstance(request.state, Failed):
    print("The task or flow failed.")
else:
    print("The task or flow did not fail.")

Please note that this is a basic example. In a real-world scenario, you would likely want to handle failures more gracefully, for example by retrying the task or flow, logging the error, or notifying someone.

@Marvin how to do so for version 2

In Prefect 2, the way to check the state of a task or flow has not changed significantly. You still use the

.state

attribute to check the state of a task or flow. However, there are some changes in the way tasks and flows are defined and run. Here's an example of how you might check the state of a task or flow in Prefect 2:

from prefect import Flow, Task
from prefect.engine.state import Failed

class MyTask(Task):
    def run(self):
        # Your task logic here
        pass

# Define your flow
with Flow("My Flow") as flow:
    task = MyTask()

# Run your flow
state = flow.run()

# Check the state
if isinstance(state, Failed):
    print("The flow failed.")
else:
    print("The flow did not fail.")

In this example,

MyTask

is a custom task defined by subclassing

Task

. The task is added to the flow in the

with Flow("My Flow") as flow:

block. The flow is run with

flow.run()

, and the state of the flow is checked with

isinstance(state, Failed)

. Please note that this is a basic example. In a real-world scenario, you would likely want to handle failures more gracefully, for example by retrying the task or flow, logging the error, or notifying someone.

@Marvin getting the error AttributeError: 'PrefectFuture' object has no attribute 'state'

Based on the information from the GitHub issues, it seems like you're encountering an issue with Prefect's

PrefectFuture

object. In Prefect 2.0, when you submit a task using

task.submit()

, it returns a

PrefectFuture

object. However, the

PrefectFuture

object does not have a

state

attribute, which is why you're seeing the

AttributeError: 'PrefectFuture' object has no attribute 'state'

error. Here's a workaround to get the state of a task:

from prefect import Flow, Task
from prefect.engine.state import Failed

class MyTask(Task):
    def run(self):
        # Your task logic here
        pass

# Define your flow
with Flow("My Flow") as flow:
    task = MyTask()

# Run your flow
state = flow.run()

# Get the state of a specific task
task_state = state.result[task].state

# Check the state
if isinstance(task_state, Failed):
    print("The task failed.")
else:
    print("The task did not fail.")

In this example,

state.result[task].state

gets the state of the

task

task. You can replace

task

with the specific task you want to check the state of. Please note that this is a workaround and might not work in all situations. If you're still having issues, I would recommend reaching out to the Prefect community for more help.

@Marvin I would like to check the state like this

if request_token.get_state().is_failed():

Without await

In Prefect 2.0, you can retrieve the state of your tasks or flows with the

return_state

keyword argument. By default, Prefect 2.0 returns function results instead of Prefect futures and states. However, if you set

return_state=True

in your flow or task call, you can access its state with the

.result()

method, even if it's been submitted to a task runner. Here's an example of how you might use this:

from prefect import Flow, Task
from prefect.engine.state import Failed

class MyTask(Task):
    def run(self):
        # Your task logic here
        pass

# Define your flow
with Flow("My Flow") as flow:
    task = MyTask()

# Run your flow and get the state
state = flow.run(return_state=True)

# Get the state of a specific task
task_state = state.result[task]

# Check the state
if task_state.is_failed():
    print("The task failed.")
else:
    print("The task did not fail.")

In this example,

flow.run(return_state=True)

runs the flow and returns its state.

state.result[task]

gets the state of the

task

task.

task_state.is_failed()

checks if the task failed. Please note that this is a basic example. In a real-world scenario, you would likely want to handle failures more gracefully, for example by retrying the task or flow, logging the error, or notifying someone.

this is right in spirit, just not quite in syntax

In [5]: from prefect import flow

In [6]: @flow
   ...: def foo():
   ...:     pass
   ...:

In [7]: state = foo(return_state=True)

14:46:01.857 | INFO    | prefect.engine - Created flow run 'uptight-labradoodle' for flow 'foo'
14:46:01.858 | INFO    | Flow run 'uptight-labradoodle' - View at <https://app.prefect.cloud/>...
14:46:02.743 | INFO    | Flow run 'uptight-labradoodle' - Finished in state Completed()

In [8]: assert state.is_completed() and not state.is_failed()