Proper types with implementing ResolverInterface and inheritance.

[valerii15298]

I am trying to implement FieldResolver while using resolver for ObjectType like this:

@ObjectType()
class Type1 {
  @Field()
  field1: string;
}

@Resolver((_of) => Type1)
class Res1 implements ResolverInterface<Type1> {
  @FieldResolver()
  async field1(@Arg('arg1') arg1: string) {
    return 'hello';
  }
}

And the problem is that you cant use Arg decorator because of implementing ResolverInterface<Type1> interface.
Typescript complains:

TS2416: Property 'field1' in type 'Res1' is not assignable to the same property in base type 'ResolverInterface<Type1>'.
Type '(arg1: string) => Promise<string>' is not assignable to type '(root: Type1, ...args: any[]) => string | Promise<string>'.
Types of parameters 'arg1' and 'root' are incompatible.
Type 'Type1' is not assignable to type 'string'.

The same but without @Arg works fine:

@ObjectType()
class Type1 {
  @Field()
  field1: string;
}

@Resolver((_of) => Type1)
class Res1 implements ResolverInterface<Type1> {
  @FieldResolver()
  async field1() {
    return 'hello';
  }
}

Is there some way to handle it? I did not found examples in docs.
I can just simply remove part implements ResolverInterface<Type1> and everything will work fine,
but maybe there is better solution to benefit from type safety?

[MichalLytek]

In 90% of cases, field resolvers are making computation based on the parent object (root in the error message).
So you can:

1. Use @Root() root: Type1 as the first parameter
2. Remove ResolverInterface
3. Write your own ResolverInterface type that does not check the first argument at all.

[valerii15298]

Thank you for such a quick answers always and clear concise explanation.