class ActiveRecord::Batches::BatchEnumerator

Public Instance Methods

delete_all() click to toggle source

Deletes records in batches. Returns the total number of rows affected.

Person.in_batches.delete_all

See Relation#delete_all for details of how each batch is deleted.

# File lib/active_record/relation/batches/batch_enumerator.rb, line 49
def delete_all
  sum(&:delete_all)
end
destroy_all() click to toggle source

Destroys records in batches.

Person.where("age < 10").in_batches.destroy_all

See Relation#destroy_all for details of how each batch is destroyed.

# File lib/active_record/relation/batches/batch_enumerator.rb, line 69
def destroy_all
  each(&:destroy_all)
end
each() { |relation| ... } click to toggle source

Yields an ActiveRecord::Relation object for each batch of records.

Person.in_batches.each do |relation|
  relation.update_all(awesome: true)
end
# File lib/active_record/relation/batches/batch_enumerator.rb, line 78
def each
  enum = @relation.to_enum(:in_batches, of: @of, start: @start, finish: @finish, load: false)
  return enum.each { |relation| yield relation } if block_given?
  enum
end
each_record() { |record| ... } click to toggle source

Looping through a collection of records from the database (using the all method, for example) is very inefficient since it will try to instantiate all the objects at once.

In that case, batch processing methods allow you to work with the records in batches, thereby greatly reducing memory consumption.

Person.in_batches.each_record do |person|
  person.do_awesome_stuff
end

Person.where("age > 21").in_batches(of: 10).each_record do |person|
  person.party_all_night!
end

If you do not provide a block to each_record, it will return an Enumerator for chaining with other methods:

Person.in_batches.each_record.with_index do |person, index|
  person.award_trophy(index + 1)
end
# File lib/active_record/relation/batches/batch_enumerator.rb, line 36
def each_record
  return to_enum(:each_record) unless block_given?

  @relation.to_enum(:in_batches, of: @of, start: @start, finish: @finish, load: true).each do |relation|
    relation.records.each { |record| yield record }
  end
end
update_all(updates) click to toggle source

Updates records in batches. Returns the total number of rows affected.

Person.in_batches.update_all("age = age + 1")

See Relation#update_all for details of how each batch is updated.

# File lib/active_record/relation/batches/batch_enumerator.rb, line 58
def update_all(updates)
  sum do |relation|
    relation.update_all(updates)
  end
end