GraphQL fails on a serialization of special float values

[fedinskiy]

Version

3.9.5

Context

When a Graphql server tries to return a special float value(NaN or one of the Infinites), it fails with the exception "Expected type 'Float' but was 'Float'."

Do you have a reproducer?

https://github.com/vert-x3/vertx-web/blob/907f4d638a01c00bcb71465c25d79094986204d3/vertx-web-graphql/src/test/java/io/vertx/ext/web/handler/graphql/ReproduceServer.java

Steps to reproduce

1. Create a GraphQL server with a Float field
2. Make the wiring return Float.NaN, Float.POSITIVE_INFINITY or Float.NEGATIVE_INFINITY for this field
3. Start the server and query the field from a client

Expected result: some data is received
Actual result: Error with message "Can't serialize value (/${fieldname}) : Expected type 'Float' but was 'Float'."

Extra

Java 8

Also, it looks like the cause of the bug lies in the GraphQL java library, which uses BigDecimal for serialization of float values. And according to its documentation, BigDecimal is unable to handle NaN and ±Infinity.

[tsegismont]

According to the spec, NaN should be transformed to null.

Can you report the issue to GraphQL-Java?

[fedinskiy]

@tsegismont, yes, will do it tomorrow.

[fedinskiy]

@tsegismont it looks like they already have issues for NaNs (graphql-java/graphql-java#1062) and for infinities (graphql-java/graphql-java#1998). If I understand correctly, the implementation was created before the specification was updated to describe a proper handling of NaNs.
As a side note, there is an ongoing proposal to remove NaNs and Infinities from the specification: graphql/graphql-spec/pull/780

[tsegismont]

@fedinskiy thanks for letting us know. I'm closing the issue as this is something that needs to be handled in either user's code or GraphQL-Java

[glasser]

@fedinskiy I'd describe my proposal as a clarification of the language in the spec rather than a removal.