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Class: ActiveRecord::Batches::BatchEnumerator

Relationships & Source Files
Super Chains via Extension / Inclusion / Inheritance
Instance Chain:
self, ::Enumerable, ::ActiveSupport::EnumerableCoreExt::Constants
Inherits: Object
Defined in: activerecord/lib/active_record/relation/batches/batch_enumerator.rb

Instance Attribute Summary

  • #finish readonly

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

  • #relation readonly

    The relation from which the BatchEnumerator yields batches.

  • #start readonly

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

::Enumerable - Included

#many?

Returns true if the enumerable has more than 1 element.

Instance Method Summary

::Enumerable - Included

#compact_blank

Returns a new ::Array without the blank items.
#exclude?

The negative of the Enumerable#include?.
#excluding

Returns a copy of the enumerable excluding the specified elements.
#in_order_of

Returns a new ::Array where the order has been set to that provided in the series, based on the key of the objects in the original enumerable.
#including

Returns a new array that includes the passed elements.
#index_by

Convert an enumerable to a hash, using the block result as the key and the element as the value.
#index_with

Convert an enumerable to a hash, using the element as the key and the block result as the value.
#maximum

Calculates the maximum from the extracted elements.
#minimum

Calculates the minimum from the extracted elements.
#pick

Extract the given key from the first element in the enumerable.
#pluck

Extract the given key from each element in the enumerable.
#sole

Returns the sole item in the enumerable.
#without

Alias for Enumerable#excluding.

Instance Attribute Details

#finish (readonly)

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

[ GitHub ] 

  


# File 'activerecord/lib/active_record/relation/batches/batch_enumerator.rb', line 21



attr_reader :finish


  








  

    #relation   (readonly)
  



  

    

The relation from which the BatchEnumerator yields batches.


  



  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/relation/batches/batch_enumerator.rb', line 24



attr_reader :relation


  








  

    #start   (readonly)
  



  

    

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


  



  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/relation/batches/batch_enumerator.rb', line 18



attr_reader :start


  







Instance Method Details



  

    #batch_size  
  



  

    

The size of the batches yielded by the BatchEnumerator.


  



  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/relation/batches/batch_enumerator.rb', line 27



def batch_size
  @of
end


  








  

    #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.


  



  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/relation/batches/batch_enumerator.rb', line 65



def delete_all
  sum(&:delete_all)
end


  








  

    #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.


  



  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/relation/batches/batch_enumerator.rb', line 85



def destroy_all
  each(&:destroy_all)
end


  








  

    #each(&block)  
  



  

    

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



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


  



  [ GitHub ]


  

  


# 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


  








  

    #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


  



  [ GitHub ]


  

  


# 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


  








  

    #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.


  



  [ GitHub ]


  

  


# 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