class RuboCop::Cop::Rails::FindBy

User.where(name: ‘Bruce’).first
# bad
@example IgnoreWhereFirst: false
User.where(name: ‘Bruce’).first
# good
@example IgnoreWhereFirst: true (default)
User.find_by(name: ‘Bruce’)
# good
User.where(name: ‘Bruce’).take
# bad
@example
If you also want to detect ‘where.first`, you can set `IgnoreWhereFirst` to false.
(They order records differently, so the “first” record can be different.)
And `where(…).first` can return different results from `find_by`.
Identifies usages of `where.take` and change them to use `find_by` instead.

def autocorrect(corrector, node) 

def autocorrect(corrector, node)
  return if node.method?(:first)
  where_loc = node.receiver.loc.selector
  first_loc = range_between(node.receiver.source_range.end_pos, node.loc.selector.end_pos)
  corrector.replace(where_loc, 'find_by')
  corrector.replace(first_loc, '')
end

def ignore_where_first? 

def ignore_where_first?
  cop_config.fetch('IgnoreWhereFirst', true)
end

def offense_range(node) 

def offense_range(node)
  range_between(node.receiver.loc.selector.begin_pos, node.loc.selector.end_pos)
end

def on_send(node) 

def on_send(node)
  return unless node.arguments.empty? && where_method?(node.receiver)
  return if ignore_where_first? && node.method?(:first)
  range = offense_range(node)
  add_offense(range, message: format(MSG, dot: node.loc.dot.source, method: node.method_name)) do |corrector|
    autocorrect(corrector, node)
  end
end

def where_method?(receiver) 

def where_method?(receiver)
  return false unless receiver
  receiver.respond_to?(:method?) && receiver.method?(:where)
end