Apply instances of relationships to nested objects.

Thanks @JoaoPedroAS51 !

You can also apply a model instance to a nested object by setting the key and the model in relations method.

If the backend responds with:

// response from API for /posts/1
{
  title: 'My title'
  body: 'Some text here',
  user: {
    firstName: 'John',
    lastName: 'Doe'
  }
}

We just need to set user to User model:

/models/Post.js

class Post extends Model {
  relations () {
    return {
      // Apply User model to `user` object
      user: User
    }
  }
}

It also works for collections. So if the backend responds with:

// response from API for /comments
{
  text: 'Some text here',
  user: {
    firstName: 'John',
    lastName: 'Doe'
  },
  replies: [
    {
      text: 'A reply here',
      user: {
        firstName: 'Joe',
        lastName: 'Doe'
      }
    },
    {
      text: 'Another reply here',
      user: {
        firstName: 'Mary',
        lastName: 'Doe'
      },
      replies: [
        {
          text: 'Yes, this is the reply of the reply!',
          user: {
            firstName: 'Max',
            lastName: 'Doe'
          }
        }
      ]
    }
  ]
}

Then we just need to set user to User model and replies to Comment model:

/models/Comment.js

class Comment extends Model {
  relations () {
    return {
      // Apply User model to `user` object
      user: User,
      // Apply Comment model to each object of `replies` array
      replies: Comment
    }
  }
}