AWS Lambda response in Java for Cognito

You just need a class like this:

import com.fasterxml.jackson.databind.annotation.JsonSerialize;
import lombok.AllArgsConstructor;
import lombok.Getter;
import lombok.NoArgsConstructor;
import lombok.Setter;

import java.util.Map;

@Getter
@Setter
@AllArgsConstructor
@NoArgsConstructor
@JsonSerialize
public class Example {
    private int version;
    private String triggerSource;
    private String region;
    private String userPoolId;
    private Map<String, String> callerContext;
    private Request request;
    private Response response;

    @Getter
    @Setter
    @JsonSerialize
    public static class Request {
        private Map<String, String> userAttributes;
        public Request(Map<String, String> userAttr) {
            userAttributes = userAttr;
        }
    }

    @Getter
    @Setter
    @JsonSerialize
    public static class Response { }

}

That after you serialize will look like this:

{
  "version" : 1,
  "triggerSource" : "trigger",
  "region" : "us-east-1",
  "userPoolId" : "user-pool-id",
  "callerContext" : {
    "some-key" : "some-value"
  },
  "request" : {
    "userAttributes" : {
      "name" : "Michael J Leonard"
    }
  },
  "response" : { }
}

And have this as an input to your lambda. It might require some changes but this is an example of a template for the PostAuthentication lambda

If you want to write your lambda in Kotlin. It's like this

Lambda:

class ClientSignupLambda : RequestHandler<PostConfirmationConfirmSignUp, PostConfirmationConfirmSignUp> {

    override fun handleRequest(event: PostConfirmationConfirmSignUp, context: Context): PostConfirmationConfirmSignUp {
        context.logger.log("event toString $event")
        return event
    }

}

Json class:

/**
 * Example of the JSON this class represents:
 * // formatterOFF
 * {
 *  version=1,
 *  region=eu-west-2,
 *  userPoolId=eu-west-2_abcd123,
 *  "userName=foo@gmail.com",
 *  "callerContext="{
 *      "awsSdkVersion=aws-sdk-unknown-unknown",
 *      clientId=123456789123456789
 *  },
 *  "triggerSource=PostConfirmation_ConfirmSignUp",
 *  "request="{
 *      "userAttributes="{
 *          sub=12341234-1234-1234-1234-123412341234,
 *          "cognito":"user_status=CONFIRMED",
 *          "email_verified=true",
 *          "name=Blundell",
 *          "email=foo@gmail.com"
 *      }
 *  },
 *  "response="{}
 * }
 * // formmatterON
 */
@Suppress("PropertyName") // Names match example, as they are used to parse JSON
class PostConfirmationConfirmSignUp {
    var version = 0
    var region: String? = null
    var userPoolId: String? = null
    var userName: String? = null
    var callerContext: CallerContext? = null
    var triggerSource: String? = null
    var request: Request? = null
    var response: Response? = null

    class CallerContext {
        var awsSdkVersion: String? = null
        var clientId: String? = null
        override fun toString(): String {
            return "CallerContext(awsSdkVersion=$awsSdkVersion, clientId=$clientId)"
        }
    }

    class Request {
        var userAttributes: UserAttributes? = null
        override fun toString(): String {
            return "Request(userAttributes=$userAttributes)"
        }
    }

    class UserAttributes {
        var sub: String? = null
        var cognito: Cognito? = null
        var email_verified: String? = null
        var name: String? = null
        var email: String? = null
        override fun toString(): String {
            return "UserAttributes(sub=$sub, cognito=$cognito, email_verified=$email_verified, name=$name, email=$email)"
        }
    }

    class Cognito {
        var user_status: String? = null
        override fun toString(): String {
            return "Cognito(user_status=$user_status)"
        }
    }

    class Response {
        override fun toString(): String {
            return "Response()"
        }
    }

    override fun toString(): String {
        return "Example(version=$version, region=$region, userPoolId=$userPoolId, userName=$userName, callContext=$callerContext, triggerSource=$triggerSource, request=$request, response=$response)"
    }
}