Class: ActiveRecord::Batches::BatchEnumerator

Inherits:
Object
  • Object
show all
Includes:
Enumerable
Defined in:
lib/active_record/relation/batches/batch_enumerator.rb

Instance Method Summary collapse

Constructor Details

#initialize(of: 1000, start: nil, finish: nil, relation:) ⇒ BatchEnumerator

:nodoc:

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# File 'lib/active_record/relation/batches/batch_enumerator.rb', line 8

def initialize(of: 1000, start: nil, finish: nil, relation:) #:nodoc:
  @of       = of
  @relation = relation
  @start = start
  @finish = finish
end

Instance Method Details

#delete_all ⇒ Object

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.

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# File 'lib/active_record/relation/batches/batch_enumerator.rb', line 49

def delete_all
  sum(&:delete_all)
end

#destroy_all ⇒ Object

Destroys records in batches.

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

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

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# File 'lib/active_record/relation/batches/batch_enumerator.rb', line 69

def destroy_all
  each(&:destroy_all)
end

#each ⇒ Object

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

Person.in_batches.each do |relation|
  relation.update_all(awesome: true)
end
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# 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 ⇒ Object

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
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# 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) ⇒ Object

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.

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# File 'lib/active_record/relation/batches/batch_enumerator.rb', line 58

def update_all(updates)
  sum do |relation|
    relation.update_all(updates)
  end
end