[TypeScript Resolvers] Apollo Server resolvers types mismatch

I use typed resolvers generation and define my resolvers like:

import { QueryResolvers, MutationResolvers, SubscriptionResolvers, User } from './generated/graphql'

const query: QueryResolvers.Resolvers = {
  allUsers: (root, args, ctx) => {
    const result: User[] = []
    return result
  }
}

const mutation: MutationResolvers.Resolvers = {
  signup: (root, args, ctx) => {
    const res = ctx.gql.mutation.createUser({
      input: {
        user: {
          firstName: 'John Doe'
        }
      }
    })
    const result: User = { firstname: 'asdf', lastname: 'asdfasdf' }
    return result
  }
}

export default {
  mutation,
  query
}

When it comes to configure apollo-server like this:

import resolvers from './app/resolvers'

const server = new ApolloServer({
      typeDefs,
      resolvers,
      mocks: true,
      context: (c: any) => ({
        ...c,
        orm: connection,
        gql: postgraphileConnection
      })
    })

then apollo-server gives an error about types mismatch:

Type '{ mutation: Resolvers<GqlContext, {}>; query: Resolvers<GqlContext, {}>; }' is not assignable to type 'IResolvers<any, any>'.
  Property 'mutation' is incompatible with index signature.
    Type 'Resolvers<GqlContext, {}>' is not assignable to type '(() => any) | GraphQLScalarType | IEnumResolver | IResolverObject<any, any> | IResolverOptions<any, any>'.
      Type 'Resolvers<GqlContext, {}>' is not assignable to type 'IResolverObject<any, any>'.
        Index signature is missing in type 'Resolvers<GqlContext, {}>'.ts(2322)

types.d.ts(28, 5): The expected type comes from property 'resolvers' which is declared here on type 'Config & { cors?: boolean | CorsOptions; }'

What should be done in order to solve it?

[esemeniuc]

For anyone wondering where to put the useIndexSignature: true, my codegen.yml looks like this (see the last 2 lines):

overwrite: true
schema: "src/schema.graphql"
documents: null
generates:
  src/generated/graphql.ts:
    plugins:
      - "typescript"
      - "typescript-resolvers"
    config:
      useIndexSignature: true

[kamilkisiela]

It’s hidden behind a flag because the type safety is less strict then.

Try useIndexSignature: true