AWS Step Functions: Filter an array using JsonPath

Question

I need to filter an array in my AWS Step Functions state. This seems like something I should easily be able to achieve with JsonPath but I am struggling for some reason.

The state I want to process looks like this:

{
  "items": [
    {
      "id": "A"
    },
    {
      "id": "B"
    },
    {
      "id": "C"
    }
  ]
}

I want to filter this array by removing entries for which id is not in a specified whitelist.

To do this, I define a Pass state in the following way:

"ApplyFilter": {
  "Type": "Pass",
  "ResultPath": "$.items",
  "InputPath": "$.items.[?(@.id in ['A'])]",
  "Next": "MapDeployments"
}

This makes use of the JsonPath in operator.

Unfortunately when I execute the state machine I receive an error:

{
  "error": "States.Runtime",
  "cause": "An error occurred while executing the state 'ApplyFilter' (entered at the event id #8). Invalid path '$.items.[?(@.id in ['A'])]' : com.jayway.jsonpath.InvalidPathException: com.jayway.jsonpath.InvalidPathException: Space not allowed in path"
}

However, I don't understand what is incorrect with the syntax. When I test here everything works correctly.

What is wrong with what I have done? Is there another way of achieving this sort of filter using JsonPath?

Answer 1

According to the official AWS docs for Step Functions,

The following in paths are not supported @ .. , : ? *

https://docs.aws.amazon.com/step-functions/latest/dg/amazon-states-language-paths.html