TypeORM does not make further query for nested object

Question

I'm currently using PostgresQL with typeORM, as well as Typegraphql. With the ManyToOne (User has many orderItems) relationship, somehow I cannot query for the nested object relation. I set the logging: true and saw that there is no SELECT query for the User entity. However, I think the query should be automatically generated giving the relation I defined in the Entity according to TypeORM.

In CartItem.ts Entity

@ObjectType()
@Entity()
export class CartItem extends BaseEntity {
  @PrimaryGeneratedColumn()
  @Field()
  id!: number;

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

  @Field(() => User, { nullable: true })
  @ManyToOne((type) => User, (user) => user.cartItems)
  user: User;

In User.ts Entity

export class User extends BaseEntity {
  @PrimaryGeneratedColumn("uuid")
  @Field()
  id!: string;

  @OneToMany((type) => CartItem, (cartItem) => cartItem.user)
  cartItems: CartItem[];

In cartItem.ts Resolver

  @Mutation(() => CartItem)
  @UseMiddleware(isAuth)
  async createCartItem(
    @Arg("input") input: CartItemInput,
    @Ctx() { req }: MyContext
  ): Promise<CartItem> {
    const newCart = await CartItem.create({
      quantity: input.quantity,
      userId: req.session.userId,
      mealkitId: input.mealkitId,
    }).save();

    return newCart;

With the following graphql Query, user would return null even though I'm supposed to get the username of the user

query cartItems{
  cartItems {
    id
    quantity
    userId
    user{
      username
    }
    
  }
}

Here is the response I received

{
  "data": {
    "cartItems": [
      {
        "id": 2,
        "quantity": 2,
        "userId": "5619ffb2-6ce2-42cf-bd5c-042f2685a045",
        "user": null
      },
      {
        "id": 1,
        "quantity": 10,
        "userId": "5619ffb2-6ce2-42cf-bd5c-042f2685a045",
        "user": null
      }
    ]
  }
}```

Answer 1

I just ran into this myself and in my query resolver I had to leftJoinAndSelect all of the sub-objects to get it to work. You aren't showing your query resolver, but something like

async cartItems(): Promise<CartItem[]> {
    return await getConnection()
        .createQueryBuilder(CartItem, 'cartItem')
        .leftJoinAndSelect('cartItem.user', 'user', 'cartItem.userId = user.id')
        .getMany()
}