Extensions example

Here’s a simple data set which would be common with data that comes from SQL sources. Notice that it has foreign key relations in it: objects in albums have the artist_id property that maps to the ID’s in artists.

Sample data

data =
  { artists:
    { 1: { id: 1, name: 'Ella Fitzgerald' },
      2: { id: 2, name: 'Frank Sinatra' },
      3: { id: 3, name: 'Miles Davis' },
      4: { id: 4, name: 'Taylor Swift' } },
    albums:
    { 1: { id: 1, name: 'Kind of Blue', genre: 'Jazz', artist_id: 3 },
      2: { id: 2, name: 'Come Fly With Me', genre: 'Jazz', artist_id: 2 },
      3: { id: 3, name: '1984', genre: 'Pop', artist_id: 4 } } }

Defining extensions

You can define extensions to traverse this intelligently, like ActiveRecord. Here, we’ll use use() to define extra methods that will be applied to certain keypaths.

Models

Root = {
  artists () { return this.go('artists') },
  albums () { return this.go('albums') }
}

Artist = {
  // Defines a has-many relationship
  albums () {
    return this.root.albums().filter({ artist_id: this.get('id') })
  }
}

Album = {
  // Defines a belongs-to relationship
  artist () {
    return this.root.artists().go(this.get('artist_id'))
  }
}

Using with scour

db = scour(data)
  .use({
    '': Root,
    'artists.*': Artist,
    'albums.*': Album
  })

Root extensions

With the extensions to the root (''), it defined an alias to go('albums') as albums().

albums = db.albums().filter({ genre: 'Jazz' })

Traversing relationships

Combined with the extensions to artists.* and albums.*, we can use it to traverse back-and-forth along “models”.

Chaining example

db
  .artists()
  .find({ name: 'Taylor Swift' })
  .albums()

Another example

albums.each((album) => {
  console.log(album.artist().get('name'))
})