[Federation] Schema built with buildFederatedSchema does not run custom scalar parseLiteral

[hannesj]

It seems custom scalars' parseLiteral is not run, when using them as inputs in a schema where federation is enabled.

I created a small repro in https://github.com/hannesj/federation-migration-example.

You can see the issue by running the server and sending the following query:

{ reservation(id: "UmVzZXJ2YXRpb24=:MQ==") { id } }

When running npm start in the before-migration/reservations directory and running the above query, the following is output, and the resolver gets the correctly typed input:

{
  kind: 'StringValue',
  value: 'UmVzZXJ2YXRpb24=:MQ==',
  block: false,
  loc: { start: 20, end: 43 }
}
TypedID { type: 'Reservation', id: '1' }

When running npm start in the after-migration/reservations directory and running the above query, the following is output, and the resolver receives an unparsed string as input:

UmVzZXJ2YXRpb24=:MQ==

[hannesj]

It seems the issue is actually in apollo-tooling. Here, the parseLiteral, parseValue and serialize functions should be copied from the GraphQLScalarType in the resolvers to the type in the schema

[jbaxleyiii]

@hannesj thanks for the reproduction and pointing to the change! Do you have any interest in making that change in a PR? We would be happy to help if you have interest!

[hannesj]

Sure, I'll take a look.

[hannesj]

@jbaxleyiii Done in apollographql/apollo-tooling#1345

[hannesj]

Released in apollo-graphql@0.3.3

[nevir]

Note that this is inconsistent vs makeExecutableSchema of old:

If you were providing "resolvers" for scalar types via makeExecutableSchema, it expected __ prefixed special functions.

const myScalarResolvers = {
  __parseValue(…) { … },
  __parseLiteral(…) { … },
  __serialize(…) { … },
};

Whereas, with buildFederatedSchema, we're assigning directly. So you'll need to convert to:

const myScalarResolvers = {
  parseValue(…) { … },
  parseLiteral(…) { … },
  serialize(…) { … },
};