AWS Step functions remove payload attribute from lambda output

Question

I have a lambda that produces an array of json objects. I want the lambda result passed to a step function under a given attribute name.

Input to task that runs lambda:

{
"foo": "abc",
"bar": "def"
}

Output I want

{
"foo": "abc",
"bar": "def",
"lambdaOutput": [
  {...},
  {...}
]
}

I thought ResultSelector + ResultPath is supposed to solve this problem but I am stuck. I tried

"ResultSelector": {
        "lambdaOutput.$": "$.Payload",
      },
      "ResultPath": "$.lambdaOutput"

But this just creates a nested structure

{
"foo": "abc",
"bar": "def",
"lambdaOutput": 
    "lambdaOutput: {
    [ 
      {...},
      {...}
    ]
    }
}

What am i missing?

Jeremy Fisher · Accepted Answer · 2023-08-06 21:11:44Z

1

Not sure how to do it from console, but from CDK, you can specify payloadResponseOnly

answered Aug 6, 2023 at 21:11

Jeremy Fisher

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Comments

Pranav Rudra · Accepted Answer · 2023-08-06 16:20:07Z

0

Disclaimer: I'm not an Amazon States Language expert, but try just:

{
  ResultPath: "$.lambdaOutput"
}

answered Aug 6, 2023 at 16:20

Pranav Rudra

735 bronze badges

That just inserts the payload inside of lambdaOutput. Anyway I found out that in CDK there is an option called payloadResponseOnly that solves this