I have a custom DataFrame type, like:

MyDataFrame = create_dagster_pandas_dataframe_type(...)

And an asset that produces that type, for storage in Snowflake. This all works as expected. The asset signature is like:

@asset
def my_asset(context: OpExecutionContext) -> MyDataFrame:
    ...
    return df

Validation passes, etc. Downstream, I have an asset that needs to understand the types specified for columns in

MyDataFrame

. I tried to do this for the downstream asset's signature:

@asset
def my_downstream_asset(context: OpExecutionContext, my_asset: MyDataFrame) -> None:
    ...
    # some stuff happens
    ...
    return None

However, I cannot materialize

my_downstream_asset

because of the error:

dagster._check.CheckError: SnowflakeIOManager does not have a handler for type 'typing.Any'. Has handlers for types '<class 'pandas.core.frame.DataFrame'>'. Please add <class 'pandas.core.frame.DataFrame'> type hints to your assets and ops.

I had this same error yesterday when I did not specify a type at all for

my_asset

in the signature of

my_downstream_asset

. How can I have

my_downstream_asset

load

my_asset

and apply the column types specified (and validated) in

MyDataFrame

?

hi @clay! this is an interesting case -- I think the issue is coming from the fact that when you use

create_dagster_pandas_dataframe_type

, it erases the information that the SnowflakeIOManager uses to determine what specific type of input object you want your table loaded as. I think this should be an easy enough fix on our end, but until that fix goes out I'd recommend just leaving the annotation off the input. If you still want to manually validate things, you can do

MyDataFrame.type_check(None, my_asset)

within the body of the asset

Awesome, thanks @owen!