Relay'd Relationship

Automatically relaying a relationship between two entities in your ORM of choice

Making a relationship relayable.

Let's say you currently have two entities / graphql objects, User and Recipe. A recipe is always linked to an user, and a given user can have multiple recipes. Your classes might look like that :

export class User {
  @PrimaryGeneratedColumn()
  @Field(() => ID)
  id: number;

  @Column()
  @Field()
  name: string;

  @OneToMany(() => Recipe)
  @Field(() => [Recipe])
  recipes: Recipe[]
}

export class Recipe {
  @PrimaryGeneratedColumn()
  @Field(() => ID)
  id: number;

  @Column()
  @Field(() => Int)
  rating: number

  @ManyToOne(() => User)
  user: User
}

With some custom logic (either lazy-loading or field resolvers) to fetch User.recipes / Recipe.user.

With AutoRelay, we're gonna replace all that logic with a single decorator, @RelayedConnection.

Our User will now look like this :

export class User {
  @PrimaryGeneratedColumn()
  @Field(() => ID)
  id: number;

  @Column()
  @Field()
  name: string;

  @OneToMany(() => Recipe)
  @RelayedConnection(() => Recipe)
  recipes: Recipe[]
}

This will auto-magically create a few GraphQL types, such as UserRecipeConnection and UserRecipeEdge. Our User.recipes field now takes Relay's ConnectionArguments and returns UserRecipeConnection!.

Our TypeORM integration gets the repository for Recipe, translates the ConnectionArguments to an offset/limit tuple and fetches recipes connected to this User.

Default sorting

@RelayedConnection can optionally accept an order parameter in its options, that will allow you to fetch while sorting on the column of your entities. For example, if we wanted to get our recipes by best ratings :

export class User {
  @PrimaryGeneratedColumn()
  @Field(() => ID)
  id: number;

  @Column()
  @Field()
  name: string;

  @OneToMany(() => Recipe)
  @RelayedConnection(() => Recipe, { order: { rating: 'DESC' } })
  recipes: Recipe[]
}

If you need more in depth sorting, check-out the docs for @auto-relay/sorting