Marcel Steinbach
02/21/2024, 9:05 AMScout
02/21/2024, 9:05 AMMarcel Steinbach
02/21/2024, 9:12 AM@asset(
deps=[A],
)
Scout
02/21/2024, 9:12 AM@asset
decorator. The deps
parameter should be used to specify the dependencies of an asset. However, if you're encountering issues with the simple deps=[A]
declaration, it might be due to how the assets are being recognized by Dagster. Here's a basic example of how to define dependencies between assets: python from dagster import asset @asset def A(): # logic for asset A pass @asset(deps=[A]) def B(A_result): # logic for asset B that depends on A pass
In this example, B
depends on A
, and the dependency is declared in the @asset
decorator of B
using deps=[A]
. Additionally, the function B
takes an argument A_result
, which corresponds to the output of asset A
. This is how Dagster knows to pass the output of A
to B
. If you're working with partitioned assets, you need to ensure that the partitions are correctly defined and that the dependencies respect those partitions. Here's an example of how you might define partitioned assets with dependencies: python from dagster import asset, DailyPartitionsDefinition partitions_def = DailyPartitionsDefinition(start_date="2021-01-01") @asset(partitions_def=partitions_def) def A(): # logic for asset A pass @asset(partitions_def=partitions_def, deps=[A]) def B(A_result): # logic for asset B that depends on A pass
In this case, both A
and B
are defined with the same DailyPartitionsDefinition
, which means they will have corresponding partitions for each day starting from "2021-01-01". If you're still encountering issues, make sure that: 1. The partition definitions for both assets are compatible and aligned. 2. The assets are correctly registered in your repository. 3. You're using the correct version of Dagster that supports the features you're using. If the problem persists, you may want to check the Dagster documentation for the most up-to-date information on defining dependencies between partitioned assets or seek help from the Dagster community.