dotansimha/graphql-code-generator

Replace `Promise` with `PromiseLike` in resolver types

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#6378 opened on Jul 29, 2021

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 (4 comments) (1 reaction) (0 assignees)TypeScript (10,341 stars) (1,295 forks)batch import
corehelp wantedkind/enhancement

Description

Is your feature request related to a problem? Please describe.

When using non-native Promise library like Bluebird, the return type of resolvers will often be PromiseLike, but it doesn't adapt with generated resolver-types because the generated code is using native Promise type.

https://github.com/dotansimha/graphql-code-generator/blob/8e4d5826df7c01fec3fa26d200d171881ee3a04a/packages/plugins/typescript/resolvers/src/index.ts#L138

sample code:

const resolvers: Resolvers = {
  Query: {
    name: () => { // string field
      return Promise.resolve('1') as PromiseLike<string>
    }
  }
}

error message:

(...omitted)
    Type 'PromiseLike<string>' is not assignable to type 'ResolverTypeWrapper<string> | Promise<ResolverTypeWrapper<string>>'.
      Type 'PromiseLike<string>' is missing the following properties from type 'Promise<ResolverTypeWrapper<string>>': catch, finally, [Symbol.toStringTag]

Describe the solution you'd like

Can Promise be just replaced with PromiseLike?

:memo: https://github.com/graphql/graphql-js/blob/0fef3c49907b63b1ea5a4ff1da7011775f465fc2/src/execution/execute.ts#L505-L506

Describe alternatives you've considered

We can customize it by using customResolverFn.

So this feature request is not mandatory, but I feel it's better if I don't have to customize and manage it in our code.

Additional context

Contributor guide

Tech stack
typescript
Domain
backend
Issue type
feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
under 1 hour
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
TypeScriptGraphQL
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
70
Research direction
Locate the file `packages/plugins/typescript/resolvers/src/index.ts` around line 138 where `Promise` is used. Replace `Promise` with `PromiseLike` to support non native promises like Bluebird. Ensure the change maintains compatibility with existing code. Check if there are other places in the codebase where similar changes are needed. Refer to the linked GraphQL js implementation for context.