Update @defer to match the latest RFC

[rmosolgo]

GraphQL-Pro's @defer and @stream implementations predate the current RFC, but since then, the proposal has been updated and the latest Apollo client has better support for it. GraphQL-Pro should be compatible with the latest spec, but also, I need some way to keep compatibility for old users.

RFC: https://github.com/graphql/graphql-wg/blob/main/rfcs/DeferStream.md

It looks to me like the only difference is whether or not it's allowed on fields -- besides that, GraphQL::Pro::Defer and GraphQL::Pro::Stream look up-to-date to me.

[felipeleusin]

There's a new version of the RFC that is about to be approved and that works better with Apollo https://github.com/graphql/graphql-spec/pull/742/files

I was struggling to get defer to work but manually constructing the multipart response with this format (using incremental) did the trick.

Apollo does send a header like multipart/mixed;deferSpec=20220824 that could be used to identify which kind of response to return.

[rmosolgo]

Interesting, thanks for sharing that, @felipeleusin. I see a couple other differences:

• @defer or @stream are not allowed on root Mutation or Subscription types
• Labels must be unique within an operation
• Subscriptions can't have @defer or @stream unless if: false is provided
• @stream payloads have items instead of data
• Defer/stream payloads should be nested in incremental: [...] instead of top-level

[rmosolgo]

GraphQL-Pro 1.24.6 added incremental: true for responding with the new JSON format.