dotansimha/graphql-code-generator

Replace `Promise` with `PromiseLike` in resolver types

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#6,378 opened on Jul 29, 2021

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 (4 comments) (1 reaction) (0 assignees)TypeScript (1,295 forks)batch import
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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

Research direction
Locate the resolver type definitions in the plugin source (packages/plugins/typescript/resolvers/src/index.ts). Replace `Promise<...>` with `PromiseLike<...>` in the relevant type aliases, such as `ResolverTypeWrapper` and any resolver function signatures. Ensure backward compatibility by considering that `PromiseLike` is a supertype of `Promise` and aligns with the GraphQL.js execution types.
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.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
Half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
TypeScriptGit
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
65