Using JayData with Ruby on Rails and YQL

Author: Janos Roden June 21st, 2012

In this example you can learn how to use a custom Ruby on Rails data source with JayData, without the need to write an own provider. You can download this Rails and JayData projects and setup your local development environment.

Ruby on Rails

We will create the server-side Ruby on Rails application and generate the following basic files:

$ rails new shop
$ cd shop
$ rails generate model Category name:string description:text --skip-timestamps
$ rails generate controller Categories index show
$ rails generate model Product category_id:integer product_name unit_price:float units_in_stock:integer discontinued:boolean --skip-timestamps
$ rails generate controller Products index show

$ rails new shop

$ cd shop

$ rails generate model Category name:string description:text --skip-timestamps

$ rails generate controller Categories index show

$ rails generate model Product category_id:integer product_name unit_price:float units_in_stock:integer discontinued:boolean --skip-timestamps

$ rails generate controller Products index show

Create and seed the database. In the nw.sql you can find the Categories and Products table of the Northwind database (the DB creation script can be found in the rails_demo/public folder inside YQLWithRails.zip, so save the nw.sql to the parent directory).

$ rake db:migrate
$ sqlite3 db/development.sqlite3 < ../nw.sql

1 2	$ rake db:migrate $ sqlite3 db/development.sqlite3 < ../nw.sql

Modify the app/controllers/categories_controller.rb file by adding XML response:

class CategoriesController < ApplicationController
  def index
    @categories = Category.all

    respond_to do |format|
      format.xml { render xml: @categories, skip_types: true, dasherize: false }
    end
  end

  def show
    @category = Category.find(params[:id])

    respond_to do |format|
      format.xml { render xml: [ @category ], skip_types: true, dasherize: false }
    end
  end
end

class CategoriesController < ApplicationController

def index

@categories = Category.all

respond_to do |format|

format.xml { render xml: @categories, skip_types: true, dasherize: false }

end

def show

@category = Category.find(params[:id])

respond_to do |format|

format.xml { render xml: [ @category ], skip_types: true, dasherize: false }

end

Do the same in the app/controllers/products_controller.rb file:

class ProductsController < ApplicationController
  def index
    conditions = []
    unless (params[:category_id].blank?)
      conditions.push('category_id = ?', params[:category_id])
    end

    @products = Product.find(:all, conditions: conditions)

    respond_to do |format|
      format.xml { render xml: @products, skip_types: true, dasherize: false }
    end
  end

  def show
    @product = Product.find(params[:id])

    respond_to do |format|
      format.xml { render xml: [ @product ], skip_types: true, dasherize: false }
    end
  end
end

class ProductsController < ApplicationController

def index

conditions = []

unless (params[:category_id].blank?)

conditions.push('category_id = ?', params[:category_id])

end

@products = Product.find(:all, conditions: conditions)

respond_to do |format|

format.xml { render xml: @products, skip_types: true, dasherize: false }

end

def show

@product = Product.find(params[:id])

respond_to do |format|

format.xml { render xml: [ @product ], skip_types: true, dasherize: false }

end

In the config/routes.rb replace the generated rules:

get "products", to: 'Products#index', format: :xml
get "products/:id", to: 'Products#show', format: :xml
get "categories", to: 'Categories#index', format: :xml
get "categories/:id", to: 'Categories#show', format: :xml

get "products", to: 'Products#index', format: :xml

get "products/:id", to: 'Products#show', format: :xml

get "categories", to: 'Categories#index', format: :xml

get "categories/:id", to: 'Categories#show', format: :xml

Now you can try out what we have so far. Start the development webserver:

$ rails server

1	$ rails server

In a different console, watch the results:

$ curl http://localhost:3000/categories --header 'Accept: application/xml'
$ curl http://localhost:3000/categories/3 --header 'Accept: application/xml'
$ curl http://localhost:3000/products --header 'Accept: application/xml'
$ curl http://localhost:3000/products?category_id=3 --header 'Accept: application/xml'
$ curl http://localhost:3000/products/3 --header 'Accept: application/xml'

$ curl http://localhost:3000/categories --header 'Accept: application/xml'

$ curl http://localhost:3000/categories/3 --header 'Accept: application/xml'

$ curl http://localhost:3000/products --header 'Accept: application/xml'

$ curl http://localhost:3000/products?category_id=3 --header 'Accept: application/xml'

$ curl http://localhost:3000/products/3 --header 'Accept: application/xml'

YQL

Publish your application to a public location where Yahoo can access it. The following two files define the Categories and Products tables. (See Open Data Tables Reference):

public/products.xml

<?xml version="1.0" encoding="UTF-8"?>
<table xmlns="http://query.yahooapis.com/v1/schema/table.xsd">
  <meta>
    <author>JayData, community@jaydata.org</author>
  </meta>
  <bindings>
	<select itemPath="products.product" produces="XML">
      <inputs>
        <key id="id" type="xs:int" paramType="path" required="false" />
        <key id="category_id" type="xs:int" paramType="query" required="false" />
      </inputs>
      <urls>
        <url><![CDATA[http://jaydata.org/examples/rails/products/{id}]]></url>
      </urls>
      <execute>
        <![CDATA[
          response.object = request.accept('application/xml').get().response;
        ]]>
      </execute>
    </select>
  </bindings>
</table>

<?xml version="1.0" encoding="UTF-8"?>

<meta>

<author>JayData, community@jaydata.org</author>

</meta>

</inputs>

<urls>

</urls>

<![CDATA[

response.object = request.accept('application/xml').get().response;

]]>

</execute>

</select>

</bindings>

</table>

public/categories.xml

<?xml version="1.0" encoding="UTF-8"?>
<table xmlns="http://query.yahooapis.com/v1/schema/table.xsd">
  <meta>
    <author>JayData, community@jaydata.org</author>
  </meta>
  <bindings>
	<select itemPath="categories.category" produces="XML">
      <inputs>
        <key id="id" type="xs:int" paramType="path" required="false" />
      </inputs>
      <urls>
        <url><![CDATA[http://jaydata.org/examples/rails/categories/{id}]]></url>
      </urls>
      <execute>
        <![CDATA[
          response.object = request.accept('application/xml').get().response;
        ]]>
      </execute>
    </select>
  </bindings>
</table>

<?xml version="1.0" encoding="UTF-8"?>

<meta>

<author>JayData, community@jaydata.org</author>

</meta>

</inputs>

<urls>

</urls>

<![CDATA[

response.object = request.accept('application/xml').get().response;

]]>

</execute>

</select>

</bindings>

</table>

Another environment file (public/tables.env):

use 'http://jaydata.org/examples/rails/categories.xml' as categories;
use 'http://jaydata.org/examples/rails/products.xml' as products;

1 2	use 'http://jaydata.org/examples/rails/categories.xml' as categories; use 'http://jaydata.org/examples/rails/products.xml' as products;

Now you can try it in the developer console: http://developer.yahoo.com/yql/console/?env=http://jaydata.org/examples/rails/tables.env

JayData

Everything is ready to use JayData to access our tables from JavaScript. Define the entities and context:

$data.Entity.extend('NorthwindModel.Category', {
    'id': { key: true, type: 'integer', nullable: false, computed: true },
    'name': { type: 'string', nullable: false, required: true, maxLength: 15 },
    'description': { type: 'string', nullable: true, maxLength: Number.POSITIVE_INFINITY },
    'products': { type: 'Array', elementType: 'NorthwindModel.Product', inverseProperty: 'category' }
});
$data.Entity.extend('NorthwindModel.Product', {
    'id': { key: true, type: 'integer', nullable: false, computed: true },
    'category_id': { type: 'integer', nullable: true },
    'product_name': { type: 'string', nullable: false, required: true, maxLength: 40 },
    'unit_price': { type: 'number', nullable: true },
    'units_in_stock': { type: 'integer', nullable: true },
    'discontinued': { type: 'boolean', nullable: false, required: true },
    'category': { type: 'NorthwindModel.Category', inverseProperty: 'products' }
});

$data.EntityContext.extend('JayDataExamples.NorthwindDB.NorthwindEntities', {
    Categories: { type: $data.EntitySet, elementType: NorthwindModel.Category, tableName: 'categories' },
    Products: { type: $data.EntitySet, elementType: NorthwindModel.Product, tableName: 'products' }
});

var northwind = new JayDataExamples.NorthwindDB.NorthwindEntities({ name: 'YQL', YQLEnv: "http://jaydata.org/examples/rails/tables.env" });

$data.Entity.extend('NorthwindModel.Category', {

'id': { key: true, type: 'integer', nullable: false, computed: true },

'name': { type: 'string', nullable: false, required: true, maxLength: 15 },

'description': { type: 'string', nullable: true, maxLength: Number.POSITIVE_INFINITY },

'products': { type: 'Array', elementType: 'NorthwindModel.Product', inverseProperty: 'category' }

});

$data.Entity.extend('NorthwindModel.Product', {

'id': { key: true, type: 'integer', nullable: false, computed: true },

'category_id': { type: 'integer', nullable: true },

'product_name': { type: 'string', nullable: false, required: true, maxLength: 40 },

'unit_price': { type: 'number', nullable: true },

'units_in_stock': { type: 'integer', nullable: true },

'discontinued': { type: 'boolean', nullable: false, required: true },

'category': { type: 'NorthwindModel.Category', inverseProperty: 'products' }

});

$data.EntityContext.extend('JayDataExamples.NorthwindDB.NorthwindEntities', {

Categories: { type: $data.EntitySet, elementType: NorthwindModel.Category, tableName: 'categories' },

Products: { type: $data.EntitySet, elementType: NorthwindModel.Product, tableName: 'products' }

});

var northwind = new JayDataExamples.NorthwindDB.NorthwindEntities({ name: 'YQL', YQLEnv: "http://jaydata.org/examples/rails/tables.env" });

Select cheap products:

northwind.Products
    .where(function (p) { p.unit_price < 10 })
    .toArray(function(cheapProducts) {
        for (var i = 0; i < cheapProducts.length; i++) {
            console.log(cheapProducts[i].product_name)
        }
    });

northwind.Products

.where(function (p) { p.unit_price < 10 })

.toArray(function(cheapProducts) {

for (var i = 0; i < cheapProducts.length; i++) {

console.log(cheapProducts[i].product_name)

}

});

Console:

Konbu
Teatime Chocolate Biscuits
Tunnbröd
Guaraná Fantástica
Geitost
Jack's New England Clam Chowder
Rogede sild
Zaanse koeken
Filo Mix
Tourtičre
Rhönbräu Klosterbier

Konbu

Teatime Chocolate Biscuits

Tunnbröd

Guaraná Fantástica

Geitost

Jack's New England Clam Chowder

Rogede sild

Zaanse koeken

Filo Mix

Tourtičre

Rhönbräu Klosterbier

examples, RoR, YQL

JayData.org