TypeGraphQL

From https://typegraphql.com/

@ObjectType()
export class Rate {
  @Field((type) => Int)
  value: number;
}

@ObjectType()
class Recipe {
  @Field()
  title: string;

  @Field({ nullable: true })
  description?: string;

  @Field((type) => [Float])
  ratings: number[];

  @Field((type) => Float, { nullable: true })
  get averageRating() {
    const sum = this.ratings.reduce((a, b) => a + b, 0);
    return sum / this.ratings.length;
  }
}

Grats

import { Float, Int } from "grats";

/** @gqlType */
class Recipe {
  /** @gqlField */
  title: string;

  /** @gqlField */
  description?: string;

  /** @gqlField */
  ratings: Float[];

  /** @gqlField */
  get averageRating(): Float | null {
    const sum = this.ratings.reduce((a, b) => a + b, 0);
    return sum / this.ratings.length;
  }
}

Playground