class RuboCop::Cop::Rails::FindBy

User.find_by(name: ‘Bruce’)
# good
User.where(name: ‘Bruce’).take
User.where(name: ‘Bruce’).first
# bad
@example
change them to use ‘find_by` instead.
This cop is used to identify usages of `where.first` and

def autocorrect(node) 

def autocorrect(node)
  receiver, second_method = where_first(node)
  # Don't autocorrect where(...).first, because it can return different
  # results from find_by. (They order records differently, so the
  # 'first' record can be different.)
  return if second_method == :first
  where_loc = receiver.loc.selector
  first_loc = Parser::Source::Range.new(
    node.source_range.source_buffer,
    node.loc.dot.begin_pos,
    node.loc.selector.end_pos
  )
  lambda do |corrector|
    corrector.replace(where_loc, 'find_by')
    corrector.replace(first_loc, '')
  end
end

def on_send(node) 

def on_send(node)
  return unless (recv_and_method = where_first(node))
  receiver, second_method = *recv_and_method
  range = Parser::Source::Range.new(node.source_range.source_buffer,
                                    receiver.loc.selector.begin_pos,
                                    node.loc.selector.end_pos)
  add_offense(node, range, format(MSG, second_method))
end