Class: ActiveMigration::Base

Inherits:
Object
  • Object
show all
Defined in:
lib/active_migration/base.rb

Overview

ActiveMigration::Base is subclassed by your migration. It defines a DSL similar to ActiveRecord, in which it feel more like a configuration.

Typical Usage:

class PostMigration < ActiveMigration::Base

  set_active_model 'Post'

  set_legacy_model 'Legacy::Post'

  map              [['name_tx',        'name'       ],
                    ['description_tx', 'description'],
                    ['date',           'created_at' ]]

end

Class Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Class Attribute Details

.active_model ⇒ Object

Returns the value of attribute active_model.



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# File 'lib/active_migration/base.rb', line 30

def active_model
  @active_model
end

.active_record_mode ⇒ Object

Returns the value of attribute active_record_mode.



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# File 'lib/active_migration/base.rb', line 30

def active_record_mode
  @active_record_mode
end

.legacy_find_options ⇒ Object

Returns the value of attribute legacy_find_options.



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# File 'lib/active_migration/base.rb', line 30

def legacy_find_options
  @legacy_find_options
end

.legacy_model ⇒ Object

Returns the value of attribute legacy_model.



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# File 'lib/active_migration/base.rb', line 30

def legacy_model
  @legacy_model
end

.mappings ⇒ Object

Returns the value of attribute mappings.



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# File 'lib/active_migration/base.rb', line 30

def mappings
  @mappings
end

Class Method Details

.map(mappings) ⇒ Object Also known as: mappings=

Sets the mappings for the migration. Mappings are specified in a multidimensional array. Each array elment contains another array in which the legacy field is the first element and the active field is the second elment.

map [['some_old_field', 'new_spiffy_field']]



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# File 'lib/active_migration/base.rb', line 80

def map(mappings)
  @mappings = mappings
end

.set_active_model(active_model, mode = :create) ⇒ Object Also known as: active_model=

Sets the active model to be migrated to.

Also, an additional parameter for the method of instantiation. Valid parameters are: :create or :update. Defaults to :create. Use this if records already exist in the active database. Lookup with :update will be done via the PK of the legacy record.

set_active_model 'Post'

set_active_model 'Post',
                 :update



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# File 'lib/active_migration/base.rb', line 68

def set_active_model(active_model, mode=:create)
  @active_model = eval(active_model)
  @active_record_mode = mode
end

.set_legacy_model(legacy_model, *args) ⇒ Object Also known as: legacy_model=

Sets the legacy model to be migrated from. It’s wise to namespace your legacy models to prevent class duplicates.

Also, *args can be passed a Hash to hold finder options for legacy record lookup.

Note: If you set :limit, it will stagger your selects with an offset. This is intended to break up large datasets to conserve memory. Keep in mind, for this functionality to work :offset(because it is needed internally) can never be specified, it will be deleted.

set_legacy_model Legacy::Post

set_legacy_model Legacy::Post,
                 :conditions => 'some_field = value',
                 :order => 'this_field ASC',
                 :limit => 5



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# File 'lib/active_migration/base.rb', line 48

def set_legacy_model(legacy_model, *args)
  @legacy_model = eval(legacy_model)
  args[0].delete(:offset) if args[0]
  @legacy_find_options = args[0] unless args.empty?
  @legacy_find_options ||= {}
end

Instance Method Details

#run ⇒ Object

Runs the migration.

MyMigration.new.run



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# File 'lib/active_migration/base.rb', line 91

def run
  logger.info("#{self.class.to_s} is starting.")
  count_options = self.class.legacy_find_options.dup
  count_options.delete(:order)
  count_options.delete(:group)
  count_options.delete(:limit)
  count_options.delete(:offset)
  @num_of_records = self.class.legacy_model.count(count_options)
  if self.class.legacy_find_options[:limit] && (@num_of_records > self.class.legacy_find_options[:limit])
    run_in_batches @num_of_records
  else
    run_normal
  end
  logger.info("#{self.class.to_s} migrated all #{@num_of_records} records successfully.")
end