I m trying to run basically this example

Question

I m trying to run basically this example <https docs dagster io concepts ops jobs graphs graphs loading an asset as an input> loading an asset as an input to a graph An `asset` definition returns an Output with a pandas Dataframe for its value Then I try to pass it to an `op` that takes a dataframe and does some work to send emails based on the contents of the dataframe But when I write a `graph` like the one in this example I get a type error `Argument of type SourceAsset cannot be assigned to parameter df of type DataFrame` And at runtime i get an error from the `op` that ` SourceAsset object has no attribute to string ` So the `op` is getting a SourceAsset not the value of the asset All the `op` examples just show the asset value getting passed directly as a parameter So Do I need to do something in the `graph` to get the Dataframe from the `SourceAsset` returned from my `asset` Or does the `op` need to take a `SourceAsset` instead of a `DataFrame` and do something to get the DataFrame out of the SourceAsset

NateV · Answer

Like in this snippet from the example what s the type of `emails` is it the asset s value like a dataframe or list or is it a SourceAsset that the `op` needs to materialize or something ``` op def send emails emails gt None ```

NateV · Answer

looks like this was dealt with recently <https github com dagster io dagster commit 5d1d12679c0471ac549165cb4a4f9379a9204f1e>

NateV · Answer

NateV · Answer

alright i got it One mistake was a silly one I d accidentally deleted or forgotten the ` op` decorator on the email sending op but it also turns out the coercion of a SourceAsset to the asset value means I can t pass other non source assets to the op function like strings or whatever Not sure what that means me Maybe i need to some sort of OpBuilder currying thing to make an op dynamically