Class: ActiveRecord::Batches::BatchEnumerator

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

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from Enumerable

#as_json, #compact_blank, #exclude?, #excluding, #in_order_of, #including, #index_by, #index_with, #many?, #maximum, #minimum, #pick, #pluck, #sole, #sum

Constructor Details

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

:nodoc:


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# File 'activerecord/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 Attribute Details

#finishObject (readonly)

The primary key value at which the BatchEnumerator ends, inclusive of the value.


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# File 'activerecord/lib/active_record/relation/batches/batch_enumerator.rb', line 19

def finish
  @finish
end

#relationObject (readonly)

The relation from which the BatchEnumerator yields batches.


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# File 'activerecord/lib/active_record/relation/batches/batch_enumerator.rb', line 22

def relation
  @relation
end

#startObject (readonly)

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


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# File 'activerecord/lib/active_record/relation/batches/batch_enumerator.rb', line 16

def start
  @start
end

Instance Method Details

#batch_sizeObject

The size of the batches yielded by the BatchEnumerator.


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# File 'activerecord/lib/active_record/relation/batches/batch_enumerator.rb', line 25

def batch_size
  @of
end

#delete_allObject

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 'activerecord/lib/active_record/relation/batches/batch_enumerator.rb', line 63

def delete_all
  sum(&:delete_all)
end

#destroy_allObject

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 'activerecord/lib/active_record/relation/batches/batch_enumerator.rb', line 83

def destroy_all
  each(&:destroy_all)
end

#each(&block) ⇒ 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 'activerecord/lib/active_record/relation/batches/batch_enumerator.rb', line 92

def each(&block)
  enum = @relation.to_enum(:in_batches, of: @of, start: @start, finish: @finish, load: false)
  return enum.each(&block) if block_given?
  enum
end

#each_record(&block) ⇒ 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 'activerecord/lib/active_record/relation/batches/batch_enumerator.rb', line 50

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).each do |relation|
    relation.records.each(&block)
  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 'activerecord/lib/active_record/relation/batches/batch_enumerator.rb', line 72

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