Ember Data JSON-API hasMany: How?

Question

I'm familiar with the old ember-data "sideloading" model, which would look like this: ```

{
  authors:[
    {id:1, name:"Ernest", type: 'author', books: [1,2]
  ],
  books: [
    {id:1, name: "For whom the bell tolls", type: 'book', author:1},
    {id:2, name: "Farewell To Arms", type: 'book', author:1}
  ]
}

But the new JSON-API method is different.

For one thing, (and I like this), attributes are separated from the id and type information, preventing namespace collisions.

I don't yet understand how to do a hasMany relationship with the JSON-API format. Can anyone point me to a doc or article on how this is expected? The examples on the JSON-API page show individual relationships, but not hasMany.

If you could write the above example in the new format, you'd have answered my question.

Answer 1

I found the answer in The JSON-API spec.

Each model should have a relationships key, whose value is an object with a key for each named relationship, which also has a data key that can be either a single object or an array for a hasMany relationship.

By providing an included key as top-level member, I can lazy load the entities.

In this case, the above example would be:

{
  "data": [
    {
      "id": 1,
      "type": "author",
      "attributes": {
        "name": "Ernest"
      },
      "relationships": {
        "books": {
          "data": [
            {
              "id": "1",
              "type": "book"
            },
            {
              "id": "2",
              "type": "book"
            }
          ]
        }
      }
    }
  ],
  "included": [
    {
      "id": 1,
      "type": "book",
      "attributes": {
        "name": "For Whom the Bell Tolls"
      },
      "relationships": {
        "author": {
          "data": {
            "id": 1,
            "type": "author"
          }
        }
      }
    },
    {
      "id": 2,
      "type": "book",
      "attributes": {
        "name": "Farewell to Arms"
      },
      "relationships": {
        "author": {
          "data": {
            "id": 1,
            "type": "author"
          }
        }
      }
    }
  ]
}

Answer 2

FYI: If you want to fetch a hashMany relationship at a later time, you have two other options.

1. Use a Related Resource Link:

As soon as the hashMany relationship is needed, Ember Data will call the backend with related link to fetch all the relations.

{
    "data": [{
        ...,
        "relationships": {
            "books": {
                "links" {
                    "related": "http://example.com/books"
                }
            }
        }
    }]
}

2. Use find-ids

As soon as the hashMany relationship is needed, Ember Data will call the backend with an url to fetch given ids. In this example it would be http://example.com/books?ids=1&ids=2

{
    "data": [{
        ...,
        "relationships": {
            "books": {
                "books": {
                    "data" [{
                        "id": "1",
                        "type": "book"
                    }, {
                        "id": "2",
                        "type": "book"
                    }]
                }
            }
        }
    }]
}