Failed to serialize CognitoUserPoolPreTokenGenerationEvent

[NikolayMetchev]

Hello,
I am trying to use cognito and a java pre-token generation event lambda https://docs.aws.amazon.com/cognito/latest/developerguide/user-pool-lambda-pre-token-generation.html

I wrote a lambda and used the following class as my lambda definition: com.amazonaws.services.lambda.runtime.RequestHandler<com.amazonaws.services.lambda.runtime.events.CognitoUserPoolPreTokenGenerationEvent, com.amazonaws.services.lambda.runtime.events.CognitoUserPoolPreTokenGenerationEvent>

this doesn't seem to be able to parse the input at all and I get the following output in the logs:

CognitoUserPoolPreTokenGenerationEvent(request=CognitoUserPoolPreTokenGenerationEvent.Request(clientMetadata=null, groupConfiguration=CognitoUserPoolPreTokenGenerationEvent.GroupConfiguration(groupsToOverride=[us-east-1_IWxv0Zfr1_Test], iamRolesToOverride=[], preferredRole=null)), response=CognitoUserPoolPreTokenGenerationEvent.Response(claimsOverrideDetails=null))

If however I use com.amazonaws.services.lambda.runtime.RequestStreamHandler I do in fact see the correct input in the lambda log. Please help

[msailes]

If you change the method to <String, String> and log out the event. What does it look like?

Obviously please don't share any sensitive details.

[NikolayMetchev]

An error occurred during JSON parsing: java.lang.RuntimeException
java.lang.RuntimeException: An error occurred during JSON parsing
Caused by: java.io.UncheckedIOException: com.amazonaws.lambda.thirdparty.com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot deserialize value of type `java.lang.String` from Object value (token `JsonToken.START_OBJECT`)
 at [Source: (ByteArrayInputStream); line: 1, column: 1]
	at com.amazonaws.services.lambda.runtime.serialization.factories.JacksonFactory$InternalSerializer.fromJson(JacksonFactory.java:176)
Caused by: com.amazonaws.lambda.thirdparty.com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot deserialize value of type `java.lang.String` from Object value (token `JsonToken.START_OBJECT`)
 at [Source: (ByteArrayInputStream); line: 1, column: 1]
	at com.amazonaws.lambda.thirdparty.com.fasterxml.jackson.databind.exc.MismatchedInputException.from(MismatchedInputException.java:59)
	at com.amazonaws.lambda.thirdparty.com.fasterxml.jackson.databind.DeserializationContext.reportInputMismatch(DeserializationContext.java:1746)
	at com.amazonaws.lambda.thirdparty.com.fasterxml.jackson.databind.DeserializationContext.handleUnexpectedToken(DeserializationContext.java:1520)
	at com.amazonaws.lambda.thirdparty.com.fasterxml.jackson.databind.DeserializationContext.handleUnexpectedToken(DeserializationContext.java:1425)
	at com.amazonaws.lambda.thirdparty.com.fasterxml.jackson.databind.DeserializationContext.extractScalarFromObject(DeserializationContext.java:937)
	at com.amazonaws.lambda.thirdparty.com.fasterxml.jackson.databind.deser.std.StdDeserializer._parseString(StdDeserializer.java:1421)
	at com.amazonaws.lambda.thirdparty.com.fasterxml.jackson.databind.deser.std.StringDeserializer.deserialize(StringDeserializer.java:48)
	at com.amazonaws.lambda.thirdparty.com.fasterxml.jackson.databind.deser.std.StringDeserializer.deserialize(StringDeserializer.java:11)
	at com.amazonaws.lambda.thirdparty.com.fasterxml.jackson.databind.deser.DefaultDeserializationContext.readRootValue(DefaultDeserializationContext.java:323)
	at com.amazonaws.lambda.thirdparty.com.fasterxml.jackson.databind.ObjectReader._bindAndClose(ObjectReader.java:2105)
	at com.amazonaws.lambda.thirdparty.com.fasterxml.jackson.databind.ObjectReader.readValue(ObjectReader.java:1481)
	at com.amazonaws.services.lambda.runtime.serialization.factories.JacksonFactory$InternalSerializer.fromJson(JacksonFactory.java:174)

[NikolayMetchev]

any news here?

[NikolayMetchev]

I have figured out what the problem is. The toString() method of CognitoUserPoolPreTokenGenerationEvent doesn't print out the object properly. It seems everything is working as expected.

[msailes]

Would you like to submit a PR?

[NikolayMetchev]

Can I get away with just a patch?

Create_toString_methods_that_call_super_toString().patch

[NikolayMetchev]

Looks like I managed to create a pull request.