Class: Lhm::Entangler

Inherits:
Object
  • Object
show all
Includes:
Command, SqlHelper
Defined in:
lib/lhm/entangler.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from SqlHelper

#annotation, #idx_name, #idx_spec, #tagged, #version_string

Methods included from Command

#run

Constructor Details

#initialize(migration, connection = nil) ⇒ Entangler

Creates entanglement between two tables. All creates, updates and deletes to origin will be repeated on the destination table.


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# File 'lib/lhm/entangler.rb', line 16

def initialize(migration, connection = nil)
  @intersection = migration.intersection
  @origin = migration.origin
  @destination = migration.destination
  @connection = connection
end

Instance Attribute Details

#connectionObject (readonly)

Returns the value of attribute connection


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# File 'lib/lhm/entangler.rb', line 12

def connection
  @connection
end

Instance Method Details

#afterObject


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# File 'lib/lhm/entangler.rb', line 86

def after
  untangle.each do |stmt|
    @connection.execute(tagged(stmt))
  end
end

#beforeObject


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# File 'lib/lhm/entangler.rb', line 80

def before
  entangle.each do |stmt|
    @connection.execute(tagged(stmt))
  end
end

#create_delete_triggerObject


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# File 'lib/lhm/entangler.rb', line 57

def create_delete_trigger
  strip %Q{
    create trigger `#{ trigger(:del) }`
    after delete on `#{ @origin.name }` for each row
    delete ignore from `#{ @destination.name }` #{ SqlHelper.annotation }
    where `#{ @destination.name }`.`id` = OLD.`id`
  }
end

#create_insert_triggerObject


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# File 'lib/lhm/entangler.rb', line 39

def create_insert_trigger
  strip %Q{
    create trigger `#{ trigger(:ins) }`
    after insert on `#{ @origin.name }` for each row
    replace into `#{ @destination.name }` (#{ @intersection.destination.joined }) #{ SqlHelper.annotation }
    values (#{ @intersection.origin.typed('NEW') })
  }
end

#create_update_triggerObject


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# File 'lib/lhm/entangler.rb', line 48

def create_update_trigger
  strip %Q{
    create trigger `#{ trigger(:upd) }`
    after update on `#{ @origin.name }` for each row
    replace into `#{ @destination.name }` (#{ @intersection.destination.joined }) #{ SqlHelper.annotation }
    values (#{ @intersection.origin.typed('NEW') })
  }
end

#entangleObject


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# File 'lib/lhm/entangler.rb', line 23

def entangle
  [
    create_delete_trigger,
    create_insert_trigger,
    create_update_trigger
  ]
end

#revertObject


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# File 'lib/lhm/entangler.rb', line 92

def revert
  after
end

#trigger(type) ⇒ Object


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# File 'lib/lhm/entangler.rb', line 66

def trigger(type)
  "lhmt_#{ type }_#{ @origin.name }"[0...64]
end

#untangleObject


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# File 'lib/lhm/entangler.rb', line 31

def untangle
  [
    "drop trigger if exists `#{ trigger(:del) }`",
    "drop trigger if exists `#{ trigger(:ins) }`",
    "drop trigger if exists `#{ trigger(:upd) }`"
  ]
end

#validateObject


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# File 'lib/lhm/entangler.rb', line 70

def validate
  unless @connection.table_exists?(@origin.name)
    error("#{ @origin.name } does not exist")
  end

  unless @connection.table_exists?(@destination.name)
    error("#{ @destination.name } does not exist")
  end
end