CODEWITHSUNDEEP
amazon-web-servicesjsonpathaws-step-functions
Emil Rowland
Emil Rowland

Reputation: 558

AWS Step Functions JSON Path filter with nested object

I'm using a Dynamodb BatchGetItem task in a AWS Step Functions state machine. I need to get the correct values from it's output as those will be used as params in the next task.

My issue is that I need to filter the result on name.S but when I do that I don't get any result. Does anyone now how to create a JSONPath that will extract the value for the corresponding key.

My Input:

{
  "Responses": {
    "Table": [
      {
        "name": {
          "S": "Param1"
        },
        "value": {
          "S": "30"
        }
      },
      {
        "name": {
          "S": "Param2"
        },
        "value": {
          "S": "40"
        }
      }
    ]
  },
  "UnprocessedKeys": {}
}

I expected something like this to work but it didn't. $..Table[?(@.name.S == Param1)].value.S -> 30.

If I would change the input to this:

{
  "Responses": {
    "Table": [
      {
        "name": "Param1",
        "value": {
          "S": "30"
        }
      },
      {
        "name": "Param2",
        "value": {
          "S": "40"
        }
      }
    ]
  },
  "UnprocessedKeys": {}
}

Then $..Table[?(@.name == Param1)].value.S -> 30 works, but I can't change the structure of the input.

Upvotes: 0

Views: 1499

Answers (1)

fedonev
fedonev

Reputation: 25669

Map over the Table items, reshaping each item with a Pass State:

{
  "StartAt": "TableItemsMap",
  "States": {
    "TableItemsMap": {
      "Type": "Map",
      "ItemsPath": "$.Responses.Table",
      "ResultPath": "$.Responses.Table",    
      "Iterator": {
         "StartAt": "ReshapePass",
         "States": {
           "ReshapePass": {
             "Type": "Pass",
             "Parameters": {
                "name.$": "$.name.S",
                "value.$": "$.value"
             },
             "End": true
           }
         }
      },
      "End": true
    }
  }
}

Upvotes: 1

Related Questions