Defining relations on nested objects

Question

Can js-data create relations on nested objects? Here is an example:

GET /card/2

{
  "id": 2,
  "name": "foo",
  "action": {     // <-- nested object
    "typeId": 1,  // foreign key to actionType.id
    "param0": 20
  }
}

GET /action-types

[{
  "id": 1,
  "name": "Jump",
  "paramsMeta": [{
     "name": "Distance",
     "max": 30
  }]
}, {
  "id": 2,
  "name": "Damage",
  "paramsMeta": [{
    "name": "amount",
    "min": 0
  }, {
    "name": "isRelative",
    "type": "Boolean"
  }]
}]

resources.js:

DS.defineResource({
  name: 'card',
  relations: {
    hasOne: {
      actionType: {
        localField: 'action.type',
        localKey: 'action.typeId'
      }
    }
  }
});

DS.defineResource(
  name: 'actionType',
  endpoint: 'action-types'
);

What I need is to initialize property card.action.type. But in current example property card['action.type'] is initialized and that's not what I want. To be more specific, current card Object after js-data processing is:

> console.log(DS.get('card', 2));
>
{
  id: 2,
  name: 'foo',
  'action.type': { id: 1, name: 'Jump', ... } // <-- reference to actionType
  action: {
    typeId: 1, param0: 20
  }
}

But I need the structure to be like this:

> console.log(DS.get('card', 2));
>
{
  id: 2,
  name: 'foo',
  action: {
    typeId: 1,
    type: { id: 1, name: 'Jump', ... }, // <-- reference to actionType
    param0: 20
  }
}

js-data version: 2.9.0

Answer 1

Problem

You need to switch from a hasOne to a belongsTo relation, e.g.:

belongsTo: {
  'action-type': {
    localField: 'action.type',
    localKey: 'action.typeId'
  }
}

Here are two plunkers that try to do what you want:

js-data v2: http://plnkr.co/edit/nbZtaXZ8AZwh9ITiG1kO?p=preview (relations on nested path, doesn't work quite right)

js-data v3: http://plnkr.co/edit/Tyxsab0icCs8nn68fkta?p=preview (relations on nested path, doesn't work quite right)

Unfortunately, JSData can't create ES5 getters for a nested path like action.type, so the links simply don't work quite as expected. (Well is does make a getter, but it ends up being a property named action.type, not what you want).

Workaround

One workaround would be to define an intermediate "action" resource, and have the following relationships:

• card belongsTo action
• action hasOne card
• action belongsTo actionType
• actionType hasMany action

The only caveat is the card.action now needs to have a primary key. The easiest thing would be to simply make card.action.id equal to card.id.

Here are two plunkers that demonstrate this workaround:

js-data v2: http://plnkr.co/edit/cUDyP0Zmk39zP30sTVpL?p=preview (relations on nested path, solved using intermediate resource)

js-data v3: http://plnkr.co/edit/J8yNL9zIp5h9RJL9XM9w?p=preview (relations on nested path, solved using intermediate resource)