How to visualize workflow structure - Prefect

You can visualize the structure of your flow using the visualize() method.

<Note> **Install Graphviz**

To use the visualize() method, you must have Graphviz installed. Please follow the Graphviz installation instructions for your platform. </Note>

python

from prefect import flow, task

@task(name="Print Hello")
def print_hello(name):
    msg = f"Hello {name}!"
    print(msg)
    return msg

@task(name="Print Hello Again")
def print_hello_again(name):
    msg = f"Hello {name}!"
    print(msg)
    return msg

@flow(name="Hello Flow")
def hello_world(name="world"):
    message = print_hello(name)
    message2 = print_hello_again(message)

if __name__ == "__main__":
    hello_world.visualize()

<Warning> **Calling `visualize()` will execute code outside of tasks**

Code outside of tasks will run when calling visualize(). To avoid inadvertent execution, place code you don't want to run in tasks. </Warning>

For workflows with dynamic structure using loops and/or if/else statements, you can provide tasks with mock return values for use in the visualize() call to choose which code paths to visualize.

python

from prefect import flow, task
@task(viz_return_value=[4])
def get_list():
    return [1, 2, 3]

@task
def append_one(n):
    return n.append(6)

@flow
def viz_return_value_tracked():
    l = get_list()
    for num in range(3):
        l.append(5)
        append_one(l)

if __name__ == "__main__":
    viz_return_value_tracked.visualize()