AWS Step Functions - Invalid JSON Path

Question

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

![Enter image description here](/media/postImages/original/IMxdrzygI1RgyStGfSgPEAdA)

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.

Accepted Answer

Hi,

AWS Step Functions uses [Amazon States Language](https://states-language.net/spec.html#path) 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.

AWS Step Functions - Invalid JSON Path

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