Methods

Included Modules

Attributes

[R] finish

The primary key value at which the BatchEnumerator ends, inclusive of the value.
[R] relation

The relation from which the BatchEnumerator yields batches.
[R] start

The primary key value from which the BatchEnumerator starts, inclusive of the value.

Instance Public methods

batch_size()

The size of the batches yielded by the BatchEnumerator.

📝 Source code 
# File activerecord/lib/active_record/relation/batches/batch_enumerator.rb, line 27
      def batch_size
        @of
      end
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delete_all()

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.

📝 Source code 
# File activerecord/lib/active_record/relation/batches/batch_enumerator.rb, line 65
      def delete_all
        sum(&:delete_all)
      end
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destroy_all()

Destroys records in batches.

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

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

📝 Source code 
# File activerecord/lib/active_record/relation/batches/batch_enumerator.rb, line 85
      def destroy_all
        each(&:destroy_all)
      end
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each(&block)

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

Person.in_batches.each do |relation|
  relation.update_all(awesome: true)
end
📝 Source code 
# File activerecord/lib/active_record/relation/batches/batch_enumerator.rb, line 94
      def each(&block)
        enum = @relation.to_enum(:in_batches, of: @of, start: @start, finish: @finish, load: false, order: @order, use_ranges: @use_ranges)
        return enum.each(&block) if block_given?
        enum
      end
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each_record(&block)

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
📝 Source code 
# File activerecord/lib/active_record/relation/batches/batch_enumerator.rb, line 52
      def each_record(&block)
        return to_enum(:each_record) unless block_given?

        @relation.to_enum(:in_batches, of: @of, start: @start, finish: @finish, load: true, order: @order).each do |relation|
          relation.records.each(&block)
        end
      end
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update_all(updates)

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.

📝 Source code 
# File activerecord/lib/active_record/relation/batches/batch_enumerator.rb, line 74
      def update_all(updates)
        sum do |relation|
          relation.update_all(updates)
        end
      end
🔎 See on GitHub