Removing duplicate records Rails 4 #rails4, #uniqueness, #accepts_nested_attributes_for

removing-duplicate-records-rails4.rb

# Related article
# http://robots.thoughtbot.com/accepts-nested-attributes-for-with-has-many-through

# Pluck ids
arr = CompanyEmployment.pluck(:company_id, :company_user_id)
#=> [[1,1], [1,2], [2,1], [2,1]]

# Select duplicates http://stackoverflow.com/a/8922408/2037928
dups = arr.select {|e| arr.rindex(e) != arr.index(e) }.uniq
#=> [[2,1]]

# Find these records and destroy them
dups.each{|d| CompanyEmployment.find_by(company_id: d[0], company_user_id: d[1]).destroy }

# Example setup

class Company < ActiveRecord::Base
  has_many :company_employments, inverse_of: :company
end

class CompanyUser < ActiveRecord::Base
  has_many :company_employments
end

class CompanyEmployment < ActiveRecord::Base
  belongs_to :company
  belongs_to :company_user

  accepts_nested_attributes_for :company_user

  validates :company,         presence: true
  validates :company_user,    presence: true
  validates :company_user_id, uniqueness: { scope: :company_id }
end