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Class: ActiveRecord::Key::Mapping

Do not use. This class is for internal use only.
Relationships & Source Files
Super Chains via Extension / Inclusion / Inheritance
Instance Chain:
self, ::Enumerable, ::ActiveSupport::EnumerableCoreExt::Constants
Inherits: Object
Defined in: activerecord/lib/active_record/key.rb

Overview

An ordered correspondence between two database keys.

Constant Summary

Class Method Summary

Instance Attribute Summary

::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.
#as_json

::ActiveSupport::EnumerableCoreExt::Constants - Included

#const_missing

Constructor Details

.new(reference_key:, target_key:) ⇒ Mapping

[ GitHub ] 

  


# File 'activerecord/lib/active_record/key.rb', line 398



def initialize(reference_key:, target_key:)
  @reference_key = reference_key
  @target_key = target_key
  if @reference_key.length != @target_key.length
    raise ArgumentError, "Key mappings must have the same number of columns"
  end
  @pairs = @reference_key.zip(@target_key).map!(&:freeze).freeze
  @hash = [@reference_key, @target_key].hash
  freeze
end


  







Class Method Details



  

    .empty  
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/key.rb', line 394



def self.empty
  EMPTY
end


  







Instance Attribute Details



  

    #empty?  ⇒ Boolean  (readonly)
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/key.rb', line 413



def empty?
  @pairs.empty?
end


  








  

    #hash   (readonly)
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/key.rb', line 445



attr_reader :hash


  








  

    #reference_key   (readonly)
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/key.rb', line 392



attr_reader :reference_key, :target_key


  








  

    #target_key   (readonly)
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/key.rb', line 392



attr_reader :reference_key, :target_key


  







Instance Method Details



  

    #+(other)  
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/key.rb', line 428



def +(other)
  return other if empty?
  return self if other.empty?

  self.class.new(
    reference_key: Key.for([*@reference_key, *other.reference_key]),
    target_key: Key.for([*@target_key, *other.target_key])
  )
end


  








  

    #==(other)  
    Also known as: #eql?
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/key.rb', line 438



def ==(other)
  other.is_a?(Mapping) &&
    reference_key == other.reference_key &&
    target_key == other.target_key
end


  








  

    #each(&block)  
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/key.rb', line 409



def each(&block)
  @pairs.each(&block)
end


  








  

    #eql?(other)  
  



  

    
Alias for #==.

  



  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/key.rb', line 443



alias_method :eql?, :==


  








  

    #normalize  
  



  

    
Returns an equivalent mapping with single-column composite keys
converted to scalar keys.

  



  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/key.rb', line 419



def normalize
  return self unless @reference_key.length == 1 && (@reference_key.composite? || @target_key.composite?)

  self.class.new(
    reference_key: @reference_key.composite? ? Key.for(@reference_key.columns.first) : @reference_key,
    target_key: @target_key.composite? ? Key.for(@target_key.columns.first) : @target_key
  )
end