How can I use Choice to test for if an input array contains a given filter?

Question

Given a Map state thats output is an array similar to the following:

[
  {
    "ProcessState": {
      "Status": "SUCCESS"
    }
  },
  {
    "ProcessState": {
      "Status": "SUCCESS"
    }
  },
  {
    "ProcessState": {
      "Status": "FAILURE"
    }
  }
]

I would like to be able to test if there is an element with Status = 'FAILURE'. I attempted to use a Choice with a choice as follows:

{
  "Variable": "$..ProcessState[?(Status == FAILURE)]",
  "IsPresent": true,
  "Next": "Items Contained Failure"
}

When attempting this I get Value is not a Reference Path: Illegal '..' ...

I'm thinking to attempt to use a Pass as an intermediate step, but I think that's just going to fail that it can't find anything if no entries match.

Answer 1

This has been solved by having the Map state ResultSelector to perform the filtering.

"ResultSelector": {
  "QueueFailures.$": "$[?(@.ProcessState.Status == 'FAILED')]"
},
"ResultPath": "$.ProcessResult"

The Choice state can now just test for the presence of the first failure item.

"Test Queue Failures": {
  "Type": "Choice",
  "Default": "Mark Decision Run Ready",
  "Choices": [
    {
      "Variable": "$.ProcessResult.QueueFailures[0]",
      "IsPresent": true,
      "Next": "Queue Contains Failures"
    }
  ]
}

While illustrating the solution but omitting much of the business case, the following puts this in the fuller context:

{
  // register our exit states
  "Failure Path": { "Type": "Fail"  },
  "Happy Path":   { "Type": "Succeed" },
  
  // map process (much removed)
  "My Map Task": {
    "Type": "Map",
    "Next": "Test Queue Failures",
    "ItemsPath": "$.Queue.Items",
    "Parameters": {
      "Item.$": "$$.Map.Item.Value"
    },

    "ResultSelector": {
      // this selector takes the error info from a batch job task.
      "QueueFailures.$": "$[?(@.ErrorInfo)]",
      "QueueItems.$": "$"
    },
    "ResultPath": "$.ProcessResult",

    "Iterator": {
      "StartAt": "First Map Item Task",
      "States": {
        "First Map Item Task": {
          "Type": "Task",
          "Resource": "arn:aws:states:::batch:submitJob.sync",
          "Next": "Complete Entry",
          // this is the key to storing the error info from the batch job
          "Catch": [
            {
              "ResultPath": "$.ErrorInfo",
              "ErrorEquals": ["States.ALL"],
              "Next": "Fail Entry"
            }
          ]
          // result selector and path omitted
        },
        
        // the following two lambdas allow me to capture state via a lambda

        // happy path for a single item iteration.
        "Complete Entry": {
          "Type": "Task",
          "Resource": "arn:aws:states:::lambda:invoke",
          "End": true,
          "OutputPath": "$.Payload"
        },

        // sad path for a single item iteration
        "Fail Entry": {
          "Type": "Task",
          "Resource": "arn:aws:states:::lambda:invoke",
          "End": true,
          "OutputPath": "$.Payload"
        }
      }
    }
  },
  
  // here we check for our fail state by finding at least 1 array being present.
  "Test Queue Failures": {
    "Type": "Choice",
    "Default": "Happy Path",
    "Choices": [
      {
        "Variable": "$.ProcessResult.QueueFailures[0]",
        "IsPresent": true,
        "Next": "Queue Contains Failures"
      }
    ]
  }

}