@Marvin, is there a way of taking a flow and generating a nice DAG visualisation?

Yes, in Prefect 3.x, you can generate a DAG visualization of your flow using the

visualize()

method. This method attempts to produce a schematic diagram of your flow and tasks without actually executing the flow. However, you need to have Graphviz installed and available on your system's PATH for this to work. You can download Graphviz from here. Here's a brief overview of how to use it:

python
from prefect import flow

@flow
def my_flow():
    # Define your tasks here
    pass

my_flow.visualize()

Note that this visualization method may not work for dynamic workflows with loops or conditional logic. In such cases, you might need to provide tasks with mock return values for the visualization. For more details, you can refer to the Prefect documentation on flow visualization.

@Marvin, for a asynchronous flow with branching, is it possible to generating a visualisation having run a flow?

Prefect's

visualize()

method is primarily designed to generate a schematic diagram of a flow before it is run. It does not support generating a visualization from a completed flow, especially for complex asynchronous flows with branching. The

visualize()

method is limited in its ability to handle dynamic workflows, such as those with loops or branching logic. If you're looking to visualize the execution path of a flow after it has run, Prefect does not natively support this functionality directly. However, you can explore logs or use Prefect's UI to gain insights into the flow's execution path and tasks. The UI provides a run history and task status that can help understand the flow's execution. For more on the visualization capabilities, refer to the Prefect documentation on flow visualization.