I had to create a complex SQL query with rails that must return an ActiveRecord::Relation

After reading over Dan Shultz presentation about Arel i decided to follow the solution he provided.

beer = Beer.arel_table

union = Beer.where(name: "Oberon") \
.union(Beer.where(name: "Two Hearted")) 

Beer.from(beer.create_table_alias(union, :beers).to_sql)

so only thing i need to add is the .to_sql call (This was needed for Arel 3.0.2 for sure)

class App.AutocompleteView extends Batman.View
  html: "<input type='text' />"
  autocompleteSource: -> []
  viewDidAppear: ->
    # I had to replace @node (as it is in the official documentation) to @node.firstChild since that is <input type='text' />
    # @node in my experiment is <div class="large-12 columns> 
    $(@node.firstChild).autocomplete
      source: @autocompleteSource()

HTML template:


</...

Given the following js model:

class MyApp.Post extends Batman.Model
  @encode options

Given the server side json (generated with rabl):

object @post
attributes :id, :category
node(:categories) {
  Category::OPTIONS.map{ |option| { id: option, name: I18n.t(option) } }
}

And finally the binded view (haml):
# This binds the selected value to the model object
%select{ "data-bind" => "post.category" }
# Iterate over categories
%option{ "data-foreach-category" =>"post.categories",
...

$context($0).controller.model_name.get('attribute_name')

To inspect a model attributes binded to a dom element
$context($("#elem-id")[0]).controller.model_name.toJSON()

Original idea taken from the link below.