resolveType factory is not compatible with Mercurius / graphql-jit

[wodCZ]

Is there an existing issue for this?

• I have searched the existing issues

Current behavior

The way the resolve-type.factory.ts is implemented breaks the compatibility with Mercurius' JIT feature.

The resolveType function is always converted to async, which is currently not supported by graphql-jit:

graphql/packages/graphql/lib/schema-builder/factories/resolve-type.factory.ts

Lines 16 to 24 in 188b83a

	return async (...args) => {
	const resolvedType = await resolveType(...args);
	if (isString(resolvedType)) {
	return resolvedType;
	}
	const typeDef =
	this.typeDefinitionsStorage.getObjectTypeByTarget(resolvedType);
	return typeDef?.type?.name;
	};

This causes requests to fail on the following:

"Abstract type Shape must resolve to an Object type at runtime for field Query.shape. Either the Shape type should provide a \"resolveType\" function or each possible types should provide an \"isTypeOf\" function."

Minimum reproduction code

https://github.com/wodCZ/nestjs-graphql-union-reproduction

Steps to reproduce

No response

Expected behavior

The resolveType function of createUnionType should be kept synchronous when defined as synchronous.

Monkey-patching the resolve-type.factory.js from

    getResolveTypeFunction(resolveType) {
        return async (...args) => {
            var _a;
            const resolvedType = await resolveType(...args);
            if ((0, shared_utils_1.isString)(resolvedType)) {
                return resolvedType;
            }
            const typeDef = this.typeDefinitionsStorage.getObjectTypeByTarget(resolvedType);
            return (_a = typeDef === null || typeDef === void 0 ? void 0 : typeDef.type) === null || _a === void 0 ? void 0 : _a.name;
        };
    }

to (async/await removed)

    getResolveTypeFunction(resolveType) {
        return (...args) => {
            var _a;
            const resolvedType = resolveType(...args);
            if ((0, shared_utils_1.isString)(resolvedType)) {
                return resolvedType;
            }
            const typeDef = this.typeDefinitionsStorage.getObjectTypeByTarget(resolvedType);
            return (_a = typeDef === null || typeDef === void 0 ? void 0 : typeDef.type) === null || _a === void 0 ? void 0 : _a.name;
        };
    }

"fixes" the issue (of course breaking real asynchronous resolveType methods.

Package version

10.0.6

Graphql version

graphql: 16.3.0
@nestjs/mercurius: 10.0.6
mercurius: 9.3.3

NestJS version

8.0.0

Node.js version

17.6.0

In which operating systems have you tested?

• macOS
• Windows
• Linux

Other

No response

[wodCZ]

It should be noted that removing resolveType function from createUnionType and returning the instance of the ObjectType directly works as expected.

(e.g. following the reproduction code):

@ObjectType()
class Square {
  @Field(() => Int)
  side: number;
}

@ObjectType()
class Circle {
  @Field(() => Int)
  radius: number;
}

const Shape = createUnionType({
  name: 'Shape',
  types: () => [Square, Circle] as const,
});

@Resolver(() => Shape)
export class AppResolver {
  @Query(() => Shape)
  shape() {
    return Object.assign(new Square(), { side: 10 });
  }
}

[kamilmysliwiec]

Let's track this here #2069