Passing Json as result path in aws Step Functions using java without escaping quotes

Question

I am using a Lambda Function within Step Functions. The function is written in Java. I want to pass multiple values similiar as in this question.

The code of the function looks like so:

public String handleRequest(S3Event event, Context context) {

//other code...

String eventJsonString = event.toJson();
JsonParser parser = new JsonParser();
JsonObject eventJson = parser.parse(eventJsonString).getAsJsonObject();
eventJson.addProperty("value1", value1);
eventJson.addProperty("value2", value2);

String output = eventJson.toString().replace("\\", "");
logger.log("output: " + output);
return output;
}

The log in CloudWatch is as expected:

output:
{
    "Records": [
        {
            "awsRegion": "eu-west-1",
            "eventName": "ObjectCreated:Put",
            "eventSource": "aws:s3",
            "eventTime": "1970-01-01T00:00:00.000Z",
            "eventVersion": "2.0",
        .
        .
        .
}

But when i go into the Step Function Console, i can see that the result was passed with escaped quotes:

"{\"Records\":[{\"awsRegion\":\"eu-west-1\",\"eventName\":\"ObjectCreated:Put\",\"eventSource\":\"aws:s3\",\"eventTime\":\"1970-01-01T00:00:00.000Z\",\"eventVersion\":\"2.0\",...}

This output can not be handled by the State Machine. I am not sure wether is this a only-java problem or also related to aws.

How can i pass the json-string with unescaped quotes, so it can be used by following components?

score 3 · Accepted Answer · answered Sep 05 '18 at 08:25

Instead of returning a String value, you can return an Object or something like a Map (using Map an example here)

public Map<String, String> handleRequest(Map<String, Object> input, Context context) {

    String brs = "42";
    String rsm = "123";

    Map<String, String> output = new HashMap<>();
    output.put("brs", brs);
    output.put("rsm", rsm);

    return output;
}

This way if you include (in the state definition)

 "ResultPath": "$.taskresult",

You will get this result in the output (along with other elements):

"taskresult": {
  "brs": "42",
  "rsm": "123"
}

Passing Json as result path in aws Step Functions using java without escaping quotes

1 Answers1