Here's how you can materialize an asset with a dynamic key in Prefect 3.x:

python
from prefect import flow, task
from prefect.assets import Asset
from prefect.utilities.annotations import materialize

@task
def determine_asset_key() -> str:
    # Your runtime logic to determine the key
    return f"dynamic-key-{some_runtime_value}"

@flow
def my_flow():
    # Get the dynamic key
    key = determine_asset_key()
    
    # Create and return the result
    result = create_asset_with_dynamic_key(key)
    return result

@materialize
def create_asset_with_dynamic_key(key: str):
    # Your asset creation logic here
    data = {"some": "data"}
    
    # Return both the data and the asset metadata
    return data, Asset(key=key)

A few key points about this approach: 1. The

@materialize

decorator is used to mark the function that will create the asset 2. The function returns a tuple containing: - The actual data/content of the asset - An

Asset

instance with the dynamic key 3. You can also include additional metadata with the asset if needed:

python
   return data, Asset(
       key=key,
       description="Dynamically generated asset",
       url="<https://your-storage-location.com/path>"
   )

This pattern gives you full flexibility to determine the asset key at runtime while still maintaining the benefits of Prefect's asset tracking and lineage features. For more details about working with assets, you can refer to the Prefect Assets documentation.