Module: Hoodoo::ActiveRecord::UUID

Defined in:
lib/hoodoo/active/active_record/uuid.rb

Overview

Support mixin for models subclassed from ActiveRecord::Base providing automatic UUID management. See:

By including this module, an on-create validation is added to the including model which assigns a UUID if none is currently set (id is nil). It also adds validations to ensure the id is present, unique and a valid UUID. You should always make sure that there are accompanying database-level uniqueness and non-null constraints on the relevant table’s ‘id` column, too.

IMPORTANT: See Hoodoo::ActiveRecord::UUID::included for important information about database requirements / table creation when using this mixin.

Class Method Summary collapse

Class Method Details

.included(model) ⇒ Object

Instantiates this module when it is included.

Example:

class SomeModel < ActiveRecord::Base
  include Hoodoo::ActiveRecord::UUID
  # ...
end
model

The ActiveRecord::Base descendant that is including this module.



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# File 'lib/hoodoo/active/active_record/uuid.rb', line 44

def self.included( model )
  instantiate( model ) unless model == Hoodoo::ActiveRecord::Base
  super( model )
end

.instantiate(model) ⇒ Object

When called, this method:

  • Declares ‘id’ as the primary key

  • Self-assigns a UUID to ‘id’ via an on-create validation

  • Adds validations to ‘id’ to ensure it is present, unique and a valid UUID.

The model MUST define its database representation in migrations so that id is a string based primary key, as follows:

create_table :model_table_name, :id => :string do | t |
  # ...your normal column definitions go here...
end

change_column :model_table_name, :id, :string, :limit => 32
model

The ActiveRecord::Base descendant that is including this module.



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# File 'lib/hoodoo/active/active_record/uuid.rb', line 68

def self.instantiate( model )
  model.primary_key = 'id'

  model.validate( :on => :create ) do
    self.id ||= Hoodoo::UUID.generate()
  end

  model.validates(
    :id,
    {
      :uuid       => true,
      :presence   => true,
      :uniqueness => true
    }
  )
end