Issue with Arrays in Downstream Mappers after a Custom Snap Transformation

[cclaudio]

We built a custom snap that performs a transformation. You will notice in the output of the custom snap in the screenshot below that “medicalEnrollment” is a json array.

In a downstream mapper, we attempted a transformation on this array. We have tried (1) using the sl.ensureArray() method and (2) another downstream mapper performing a transformation in the array. However, we notice that in both the #1 and #2 attempts the mappers do not detect the array, thus causing issues with the transformation.

Below is a snippet of the preview of what we expect vs actual preview.

We also notice that chaining a Json Formatter and a Json Parser right after the custom snap does indeed makes the mappers work correctly. Pattern shown below:

So my question is, is there something hidden in the JSON parser snap that allows strong typing of the array that we are missing? Anything in between?

@robin , Tagging you since I was told you might be able to help out. Thanks!

[ptaylor]

When I try to execute either of those pipelines the first snap fails. I think it needs an account.

[cclaudio]

@ptaylor Apologies for the incomplete copy. I uploaded the dummy file to the folder and linked it.

[ptaylor]

Would you be willing to share the binary snap pack for your custom snaps so I can run this on my local development plex and see what’s going on? If so: ptaylor@snaplogic.com

[cclaudio]

@ptaylor Will do!

[ptaylor · Accepted solution]

Thanks. I installed the binary snap pack and set a breakpoint in the Mapper to see the Java types used in the input, which is the output of your snap. I can see that medicalEnrollment is still a HashSet, not an ArrayList:

I haven’t studied your source code but I can see that you’re still using HashSet in a lot of places. Don’t use that type anywhere in your Document data. It’s not compatible with any of the JSON types. Use ArrayList everywhere you need an array.