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Title
# ask-ai
s

Shane Keller

03/06/2024, 10:05 PM
what's the difference between @asset deps and ins
s

Scout

03/06/2024, 10:05 PM
The
@asset
decorator in Dagster is used to define software-defined assets. When defining assets, you may need to specify dependencies to indicate how assets relate to each other. In Dagster, there are two ways to specify dependencies for assets:
deps
and
ins
. 1. `deps`: The
deps
parameter is used to specify dependencies between assets. When you use
deps
, you directly pass other asset functions to indicate that the asset being defined depends on the outputs of those assets. This is a newer API that allows for better type checking and error detection at development time because it directly references asset functions. 2. `ins`: The
ins
parameter is an older way to specify dependencies and has been deprecated in favor of
deps
. It used to rely on string matching asset names, which could lead to typos and errors that were only caught at runtime. The
ins
parameter allowed you to specify dependencies by providing a dictionary where the keys are the input names and the values are instances of
AssetKey
or
AssetIn
. The documentation suggests using
deps
over
ins
because it provides a more robust and error-resistant way to define dependencies between assets. The
deps
parameter accepts assets directly, which allows in-editor type checkers to detect errors, whereas
ins
relied on string matching and was more prone to runtime errors. Here's an example from the documentation showing the transition from the old API to the improved API: Old API using
non_argument_deps
(similar to
ins
):
Copy code
python @asset(non_argument_deps={"iris_dataset"}) def iris_setosa(duckdb: DuckDBResource) -> None:     ...
Improved API using `deps`:
Copy code
python @asset(deps=[iris_dataset]) def iris_setosa(duckdb: DuckDBResource) -> None:     ...
In this example,
iris_dataset
is another asset that
iris_setosa
depends on. The
deps
parameter replaces the use of
non_argument_deps
, and
non_argument_deps
has been marked deprecated. The
deps
parameter allows for better error detection and code clarity.
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