How to resolve different cache keys in list of array?

[nghiepdev]

Hi guys,

I have an example:

GraphQL schema

type Product {
   id: ID!
   name: String!
   price: Int!
}

type Order {
   id: ID!
   total: Int!
   products: [Product]
}

type Query {
   orders: [Order]
}

Request list of orders query

const GET_ORDER_LIST = gql`
  query GetOrderList{
    orders {
      id
      total
      products {
         id
         name
         price
      }
    }
  }
`;

Sample data

Order 1: {
 id: 1,
 product_ids: [1, 2]
}

Order 2: {
 id: 2,
 product_ids: [2, 3]
}

Problem: Order 1 and Order 2 both have the product_id=2 but different price value.

When rendering to the frontend the price of product_id=2 in the ofOrder2 overwrite the price of Order1.
Because the Product type has the same id value.
How to resolve different the Product type in the list of orders?

[nghiepdev]

Currently, I resolve the Product type is null instead of id.

const cache = cacheExchange({
   keys: {
      Product(data) {
         return null;
         // return data.id;
      }
   }
});

[kitten]

I think this is a change you'll want to make to your schema. All your types have a field called id which indicates that it's a globally unique value, however it's instead an index.

That also means that you can't actually share these types in a normalised form. They're dependent on the Liston which they are if that's their only ID field, so returning null here is correct which makes them embedded data

[nghiepdev]

tks @kitten
But it would be nice if there was another way like that

const cache = cacheExchange({
   keys: {
      Product(data) {
         if(isChildOfAnother) {
             return null;
         }
         return data.id;
      }
   }
});

[kitten]

Oh, I see; while this is in theory possible for us to add, we do have some opinions on how our normalised caching is implemented which is why it's not possible and those are all based on lowering the likelihood of mistakes and predictability.

I'd actually say this case sounds like you may want to introduce a new type that only is like products or add some kind of ProductEdge which is common in Relay-compliant schemas, since that'd give you a type that can carry information about the specific item in the list

The reason why I think it's odd to have this choice in the first place is that as a human reading this I see two identical products with different data, so a solution like the above (or even a separate edge or line item) result also intuitively makes more sense