AWS Step Functions - Invalid JSON Path

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I am getting the following error when attempting to use the following JSON Path in my ResultsSelector $.Clusters[:].ClusterIdentifier.

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What is curious to me is that in the Step Function Data Flow simulator, the results work as expected when testing the path selection, so I am at a loss as to how to proceed.

In the end, I want to use Describe Clusters to get the data on what is running and inspect the created array to determine if my cluster of interest is running.

asked a year ago372 views
1 Answer
0
Accepted Answer

Hi,

AWS Step Functions uses Amazon States Language to describe state machines declaratively, and the "@", ",", ":", and "?" operators are not supported, since all reference Paths MUST be unambiguous references to a single value, array, or object (subtree).

Thus, the wildcard symbol could be employed to select all elements of an object or array.

Step Function definition

{
  "Comment": "A description of my state machine",
  "StartAt": "Pass",
  "States": {
    "Pass": {
      "Type": "Pass",
      "End": true,
      "Parameters": {
        "clusterids.$": "$.Clusters[*].ClusterIdentifier"
      }
    }
  }
}

Input

{
  "Clusters": [
    {
      "ClusterIdentifier": 1
    },
    {
      "ClusterIdentifier": 2
    }
  ]
}

Output

{
  "clusterids": [
    1,
    2
  ]
}

I hope this helps you.

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EXPERT
answered a year ago
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EXPERT
reviewed a year ago
  • Ahh, I even scanned the spec and totally didn't pick up on that, especially since data were returned in the data flow simulator. Regardless, thank you for the note!

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