FlattenRecord

An ActiveRecord plugin that denormalizes your existing ActiveRecord models.

It provides an easier way to create denormalized records to be used for reporting, includes generation of migration file.

Usage

Add gem dependency

gem 'flatten_record'

Include module in your newly defined model

include FlattenRecord::Flattener

Define denormalization

class DenormalizedOrder < ActiveRecord::Base
    include FlattenRecord::Flattener

    denormalize :order, {
        include: { 
            # :belongs_to association
            customer: {}

            # :has_many association, create multiple denormalized records  
            line_items: {}
        },
        methods: {
            # save methods defined in Normalized model
            total_in_usd: :decimal 
        },
        compute: {
            # compute methods defined in Denormalized model
            line_items_sum: { type: :decimal, default: 0 } 
        }
    }

    private
    def compute_line_items_sum(order)
        order.line_items.collect(&:total).inject(:+)
    end
end

class Order < ActiveRecord::Base
    def total_in_usd
        # calculation
    end
end

Generate migration file

Generate migration file based on the definition

$ rails generate flatten_record:migration denormalized_order
  create  db/migrate/20140313034700_create_table_denormalized_orders.rb     

Update definition and generate new migration file

$ rails generate flatten_record:migration denormalized_order
Warning. Table already exists: denormalized_orders
Generating migration based on the difference..
Add columns: d_line_items_description
  create  db/migrate/20140313034736_add_d_line_items_description_to_denormalized_orders.rb      

Use denormalizer methods

Create record

irb(main)> DenormalizedOrder.create_with(order)

Deleting record(s)

irb(main)> DenormalizedOrder.destroy_with(order)

Update record(s)

irb(main)> DenormalizedOrder.update_with(order)

Design & Documentation

Refer to the wiki.

Versions

v1

• tree-based denormalization: nicer code & structure √
• new DSL + syntax √
  (Credit to @scottharvey's issue #6)
• added :prefix option - use your own column prefix √
  
• added :methods option - save normalized model's method √
  (Credit to @scottharvey's idea)
• change to old :save option to :compute option √
  (Credit to @scottharvey's idea)
• deprecate observer √
  

v0

• denormalize fields and nested fields √
  
• denormalize belongs_to, has_many typed associations √
  
• generate migration from denormalized model √
  
• observe model changes and update denormalized model √
  

Contributors

• @scottharvey

License

see MIT-LICENSE.