URQL graphql-codegen should support @defer

[jtwigg]

Hope this is the right place, but for @graphql-codegen/typescript-urql
there should be some support for @defer because it can break the typescript contract.

Example:

type Song {
  firstVerse: String!
  secondVerse: String!
}

query SongQuery{
    song {
      firstVerse
      ... @defer {
        secondVerse
      }
    }
}

generates:

export type SongQueryQuery = {
  __typename: "Query"
    song?:
      | { __typename: "Song"; secondVerse: string; firstVerse: string }
      | undefined
}

HOWEVER
because secondVerse is deferred, its undefined in the first response, and present in the second response.

{
  "firstVerse": "Now I know my ABCs",
  "__typename": "Song"
}

followed by

{
  "firstVerse": "Now I know my ABCs",
  "__typename": "Song",
  "secondVerse": "Next time won't you sing with me"
}

This means I have to be manually defensive for all of the deferred items in my query.

Possible solutions are

1. Force it to be undefined

{ __typename: "Song"; secondVerse: string | undefined; firstVerse: string }

2. It could possibly be special named __deferred

{ __typename: "Song"; secondVerse: string | "__deferred"; firstVerse: string }

3. A poorly explored idea of a Promise response could work for PromiseLike responses.. but it might not play well with react hooks.

{ __typename: "Song"; secondVerse: Promise<string> | string ; firstVerse: string }

[JoviDeCroock]

The GraphQL code generator repo is probably a better place to inquire about this. Do note that defer/stream is still not stable so it might not be a priority

[jtwigg]

I did find something on this.

dotansimha/graphql-code-generator#7885

Also, the API has been hardened substantially,
#2995 (comment)