Example of Kraken's EAV at work

kraken-example.rb

# products:
#   - _id
#   - name
#   - kraken_id
#   - parent_id
class Product
  include Mongoid::Document
  include Mongoid::Kraken
  field :name, :type => String
end

# create a Kraken object
k_product = Mongoid::Kraken::Kraken.create(:name => "Item")

# create a few Tentacle objects ("sucker" defaults to "String")
k_product.tentacles.create(:name => "description")
k_product.tentacles.create(:name => "posted_at", :sucker => DateTime)
k_product.tentacles.create(:name => "sku", :sucker => Integer)

# four different Krakens with inheritance of Tentacles
k_lighting = k_product.children.create(:name => "Lighting")
k_lighting.tentacles.create(:name => "color", :sucker => Array)

k_part = k_product.children.create(:name => "Part")
k_part.tentacles.create(:name => "part_number", :sucker => Integer)

k_shade = k_part.children.create(:name => "Shade")
k_shade.tentacles.create(:name => "style")
k_shade.tentacles.create(:name => "perimeter", :sucker => Float)

k_lamp = k_lighting.children.create(:name => "Lamp")
k_lamp.tentacles.create(:name => "shade_id", :sucker => BSON::ObjectId)

# creating of Products
p1 = Product.create(:name => "Shade (Round)",  :kraken => k_shade)
p2 = Product.create(:name => "Shade (Square)", :kraken => k_shade)

p3 = Product.create(:name => "My Round Lamp",  :kraken => k_lamp)
p4 = Product.create(:name => "My Square Lamp", :kraken => k_lamp)

# setting Product attributes
p1.description = "Round and round"
p1.posted_at = Time.now
p1.sku = 1000
p1.part_number = 100
p1.style = "round"
p1.perimeter = (2 * Math::PI) * 10
p1.save

p2.description = "Don't be a square"
p2.posted_at = Time.now
p2.sku = 1001
p2.part_number = 101
p2.style = "square"
p2.perimeter = 4.0 * 5.5
p2.save

p3.description = "It's very, very round."
p3.posted_at = Time.now
p3.sku = 1236
p3.color = [ 255, 0, 0 ]
p3.shade_id = p1['_id']
p3.save

p3.shade.name # => "Shade (Round)"

p4.description = "My other square lamp."
p4.posted_at = Time.now
p4.sku = 1237
p4.color = [ 0, 0, 255 ]
p4.shade_id = p2.id
p4.save

p4.shade.name # => "Shade (Square)"

# What Tentacles have been inherited?
p1.kraken.all_tentacles.flatten.map(&:name)
# => ["style", "perimeter", "part_number", "description", "posted_at", "sku"] 
p1.kraken_fields.keys
# => ["style", "perimeter", "part_number", "description", "posted_at", "sku"] 

p2.kraken.all_tentacles.flatten.map(&:name)
# => ["style", "perimeter", "part_number", "description", "posted_at", "sku"] 
p2.kraken_fields.keys
# => ["style", "perimeter", "part_number", "description", "posted_at", "sku"] 

p3.kraken.all_tentacles.flatten.map(&:name)
# => ["shade_id", "color", "description", "posted_at", "sku"]
p3.kraken_fields.keys 
# => ["shade_id", "color", "description", "posted_at", "sku"] 

p4.kraken.all_tentacles.flatten.map(&:name)
# => ["shade_id", "color", "description", "posted_at", "sku"]
p4.kraken_fields.keys
# => ["shade_id", "color", "description", "posted_at", "sku"]

mongoid_kraken_krakens.json

/* 0 */
{
  "_id": {
    "$oid": "4d8e2be428c69b43d2000001"
  },
  "name": "Item",
  "tentacle_ids": [
    {
      "$oid": "4d8e2be928c69b43d2000002"
    },
    {
      "$oid": "4d8e2be928c69b43d2000003"
    },
    {
      "$oid": "4d8e2bea28c69b43d2000004"
    }
  ]
}

/* 1 */
{
  "_id": {
    "$oid": "4d8e2bef28c69b43d2000005"
  },
  "name": "Lighting",
  "parent_id": {
    "$oid": "4d8e2be428c69b43d2000001"
  },
  "tentacle_ids": [
    {
      "$oid": "4d8e2bef28c69b43d2000006"
    }
  ]
}

/* 2 */
{
  "_id": {
    "$oid": "4d8e2bef28c69b43d2000007"
  },
  "name": "Part",
  "parent_id": {
    "$oid": "4d8e2be428c69b43d2000001"
  },
  "tentacle_ids": [
    {
      "$oid": "4d8e2bef28c69b43d2000008"
    }
  ]
}

/* 3 */
{
  "_id": {
    "$oid": "4d8e2bef28c69b43d2000009"
  },
  "name": "Shade",
  "parent_id": {
    "$oid": "4d8e2bef28c69b43d2000007"
  },
  "tentacle_ids": [
    {
      "$oid": "4d8e2bef28c69b43d200000a"
    },
    {
      "$oid": "4d8e2bef28c69b43d200000b"
    }
  ]
}

/* 4 */
{
  "_id": {
    "$oid": "4d8e2bef28c69b43d200000c"
  },
  "name": "Lamp",
  "parent_id": {
    "$oid": "4d8e2bef28c69b43d2000005"
  },
  "tentacle_ids": [
    {
      "$oid": "4d8e2bf028c69b43d200000d"
    }
  ]
}

mongoid_kraken_tentacles.json

/* 0 */
{
  "_id": {
    "$oid": "4d8e2be928c69b43d2000002"
  },
  "sucker": "String",
  "name": "description"
}

/* 1 */
{
  "_id": {
    "$oid": "4d8e2be928c69b43d2000003"
  },
  "sucker": "DateTime",
  "name": "posted_at"
}

/* 2 */
{
  "_id": {
    "$oid": "4d8e2bea28c69b43d2000004"
  },
  "sucker": "Integer",
  "name": "sku"
}

/* 3 */
{
  "_id": {
    "$oid": "4d8e2bef28c69b43d2000006"
  },
  "sucker": "Array",
  "name": "color"
}

/* 4 */
{
  "_id": {
    "$oid": "4d8e2bef28c69b43d2000008"
  },
  "sucker": "Integer",
  "name": "part_number"
}

/* 5 */
{
  "_id": {
    "$oid": "4d8e2bef28c69b43d200000a"
  },
  "sucker": "String",
  "name": "style"
}

/* 6 */
{
  "_id": {
    "$oid": "4d8e2bef28c69b43d200000b"
  },
  "sucker": "Float",
  "name": "perimeter"
}

/* 7 */
{
  "_id": {
    "$oid": "4d8e2bf028c69b43d200000d"
  },
  "sucker": "BSON::ObjectId",
  "name": "shade_id"
}

products.json

/* 0 */
{
  "_id": {
    "$oid": "4d8e2bf728c69b43d200000e"
  },
  "description": "Round and round",
  "kraken_id": {
    "$oid": "4d8e2bef28c69b43d2000009"
  },
  "name": "Shade (Round)",
  "part_number": 100,
  "perimeter": 62.831853071795862,
  "posted_at": "Sat, 26 Mar 2011 12:10:07 GMT -06:00",
  "sku": 1000,
  "style": "round"
}

/* 1 */
{
  "_id": {
    "$oid": "4d8e2bf728c69b43d200000f"
  },
  "description": "Don't be a square",
  "kraken_id": {
    "$oid": "4d8e2bef28c69b43d2000009"
  },
  "name": "Shade (Square)",
  "part_number": 101,
  "perimeter": 22,
  "posted_at": "Sat, 26 Mar 2011 12:10:07 GMT -06:00",
  "sku": 1001,
  "style": "square"
}

/* 2 */
{
  "_id": {
    "$oid": "4d8e2bf728c69b43d2000010"
  },
  "color": [
    255,
    0,
    0
  ],
  "description": "It's very, very round.",
  "kraken_id": {
    "$oid": "4d8e2bef28c69b43d200000c"
  },
  "name": "My Round Lamp",
  "posted_at": "Sat, 26 Mar 2011 12:10:07 GMT -06:00",
  "shade_id": {
    "$oid": "4d8e2bf728c69b43d200000e"
  },
  "sku": 1236
}

/* 3 */
{
  "_id": {
    "$oid": "4d8e2bf828c69b43d2000011"
  },
  "color": [
    0,
    0,
    255
  ],
  "description": "My other square lamp.",
  "kraken_id": {
    "$oid": "4d8e2bef28c69b43d200000c"
  },
  "name": "My Square Lamp",
  "posted_at": "Sat, 26 Mar 2011 12:10:18 GMT -06:00",
  "shade_id": {
    "$oid": "4d8e2bf728c69b43d200000f"
  },
  "sku": 1237
}