Battling RecordNotUnique in Rails

application_record.rb

class ApplicationRecord < ActiveRecord::Base
  attr_writer :created_moments_ago

  def created_moments_ago?
    @created_moments_ago
  end

  def self.create_or_take!
    where(block_given? && yield).crumby_create!
  rescue ActiveRecord::RecordNotUnique
    take!
  end

  def self.crumby_create!
    instance = transaction(requires_new: true) { create! }
    instance.created_moments_ago = true
    instance
  end

  def self.take_or_create!(&block)
    take || create_or_take!(&block)
  end
end

# INSERT first. If INSERT fails, try to SELECT
Model.where(unique_attr: val)
  .create_or_take! { creation_attrs_hash }

# SELECT first, then INSERT
# if INSERT fails, try to SELECT one more time
Model.where(unique_attr: val)
  .take_or_create! { creation_attrs_hash }


model = Model.where(unique: val).take_or_create! { '...' }
model.created_moments_ago?

record_not_unique_example.rb

# Model.where(unique_col: val)
#   .first_or_create { |new_record| ... }

# first_or_create

def example_1
  begin
    Model.where(...).first_or_create { '...' }
  rescue ActiveRecord::RecordNotUnique => exception
    # Retry first_or_create here.
    # Blow up if still not found (broken code).
  end
end

def example_2
  begin
    tries ||= 0
    Model.where(...).first_or_create { '...' }
  rescue ActiveRecord::RecordNotUnique => exception
    retry if (tries += 1) == 1
    raise exception
  end
end

# create_or_find_by

Model.where(unique_attr: val).create_or_find_by do |new_record|
  new_record.assign_attributes(initial_attributes)
end