EmberJS JSONAPIAdapter with hasMany + embedded relationships

Question

In addition to my last question ember.js JSONAPIAdapter with hasMany a colleague asked if the "kind-of"-sideloaded relationships in the working JSON:API structure could be embedded like this:

{
    "data": [
      {
        "type": "altersgruppe",
        "id": "1",
        "attributes": {
          "name": "UNTER_21"
        },
        "relationships": {
          "tarifbeitraege": {
            "data": [
              {
                "type": "tarifbeitrag",
                "id": "3",
                "attributes": {
                  "name": "ZAHN70",
                  "beitrag": "3-29,70",
                  "proergaenzung": "7,00",
                  "gesamtbeitrag": "25.99"
                }
              },
              {
                "type": "tarifbeitrag",
                "id": "4",
                "attributes": {
                  "name": "ZAHN90",
                  "beitrag": "4-28,70",
                  "proergaenzung": "7,00",
                  "gesamtbeitrag": "30.99"
                }
              }
            ]
          }
        }
      },
      {
        "type": "altersgruppe",
        "id": "2",
        "attributes": {
          "name": "ALTER_21_24"
        },
        "relationships":{
          "tarifbeitraege": {
            "data": [
              {
                "type": "tarifbeitrag",
                "id": "1",
                "attributes": {
                  "name": "ZAHN70",
                  "beitrag": "1-25,70",
                  "proergaenzung": "7,00",
                  "gesamtbeitrag": "25.99"
                }
              },
              {
                "type": "tarifbeitrag",
                "id": "2",
                "attributes": {
                  "name": "ZAHN90",
                  "beitrag": "2-25,70",
                  "proergaenzung": "7,00",
                  "gesamtbeitrag": "25.99"
                }
              }]
          }
        }
      }
    ]
}

The idea behind that: We can use relationships with less problems in the java backend (where sideloaded structures are harder to implement).

But the JSON above structure does not work. The store contains only the first level of data, which is "altersgruppe", but "tarifbeitraege" are empty.

Answer 1

This type of document is referred to as a compound document in the JSON:API specification.

The "relationships" section of a compound document is supposed to have only the relationships - individual objects there are supposed to be resource identifier objects. Putting attributes there doesn't work because that's not where they are supposed to be.

Instead, the full objects are side-loaded in a top-level "included" section. Thus, your response should probably look more like this:

{
    "data": [
      {
        "type": "altersgruppe",
        "id": "1",
        "attributes": {
          "name": "UNTER_21"
        },
        "relationships": {
          "tarifbeitraege": {
            "data": [
              { "type": "tarifbeitrag", "id": "3" },
              { "type": "tarifbeitrag", "id": "4" }
            ]
          }
        }
      },
      {
        "type": "altersgruppe",
        "id": "2",
        "attributes": {
          "name": "ALTER_21_24"
        },
        "relationships":{
          "tarifbeitraege": {
            "data": [
              { "type": "tarifbeitrag", "id": "1" },
              { "type": "tarifbeitrag", "id": "2" }
              ]
           }
        }
      }
    ],
    "included": [
      {
        "type": "tarifbeitrag",
        "id": "3",
        "attributes": {
          "name": "ZAHN70",
          "beitrag": "3-29,70",
          "proergaenzung": "7,00",
          "gesamtbeitrag": "25.99"
        }
      },
      {
        "type": "tarifbeitrag",
        "id": "4",
        "attributes": {
          "name": "ZAHN90",
          "beitrag": "4-28,70",
          "proergaenzung": "7,00",
          "gesamtbeitrag": "30.99"
        }
      },
      {
        "type": "tarifbeitrag",
        "id": "1",
        "attributes": {
          "name": "ZAHN70",
          "beitrag": "1-25,70",
          "proergaenzung": "7,00",
          "gesamtbeitrag": "25.99"
        }
      },
      {
        "type": "tarifbeitrag",
        "id": "2",
        "attributes": {
          "name": "ZAHN90",
          "beitrag": "2-25,70",
          "proergaenzung": "7,00",
          "gesamtbeitrag": "25.99"
        }
      }
    ]
}

There's an example on the home page of http://jsonapi.org that shows an example that includes a side load, as well as one in the section of the specification describing compound documents.