Graphql graph.cool双向绑定

我只是从

graph.cool

开始，我正试图在

graph.cool

的帮助下构建一个graphql数据模型。 似乎我们总是需要进行双向绑定。 例如

User->Posts或Posts->User.

我做了一个这样的结构：

type User @model {
  id: ID! @isUnique
  name: String
  cart: Cart @relation(name: "UserCart")
}
type Category @model {
  id: ID! @isUnique
  name: String!
  image: String
  description: String
  subCategories: [SubCategory!]! @relation(name: "CategoriesSubCategories")
}
type SubCategory @model {
  id: ID! @isUnique
  name: String!
  products: [Product!]! @relation(name: "SubCategoryProduct")
  category: Category! @relation(name: "CategoriesSubCategories")
}

type Product @model {
  id: ID! @isUnique
  name: String
  image: String
  description: String
  basePrice: Int
  subCategory: SubCategory @relation(name: "SubCategoryProduct")
}

type Cart @model {
  id: ID! @isUnique
  cartItems: [CartItem!]! @relation(name: "CartItems")
  user: User! @relation(name: "UserCart")
}

type CartItem @model {
  id: ID! @isUnique
  quantity: Int
  #i need to do two way binding for this
  product: Product @relation(name: "CartItemProduct")
  # -----
  cart: Cart! @relation(name: "CartItems")
}

一切如期而至。但是当我创建cartItems时，它有一个Product属性，我不知道如何将它与创建cart的用户连接。 我们将不胜感激

CartItem
    ✖ A relation directive with a name must appear exactly 2 times. Relation name: 'CartItemProduct'