Chaining styles.

chaining-1.rb

school.schools_users
  .joins("LEFT JOIN users ON users.id = schools_users.user_id")
  .where(self.filters)
  .where(self.search_string)
  .order(order)

chaining-2.rb

school
  .schools_users
  .joins("LEFT JOIN users ON users.id = schools_users.user_id")
  .where(self.filters)
  .where(self.search_string)
  .order(order)

chaining-3.rb

school.schools_users.joins("LEFT JOIN users ON users.id = schools_users.user_id")
                    .where(self.filters)
                    .where(self.search_string)
                    .order(order)

chaining-4.rb

school.schools_users.joins("LEFT JOIN users ON users.id = schools_users.user_id").where(self.filters).where(self.search_string).order(order)

chaining-5.rb

q = school.schools_users
q = q.joins("LEFT JOIN users ON users.id = schools_users.user_id")
q = q.where(self.filters)
q = q.where(self.search_string)
q = q.order(order)

I like the 3rd option.

First option

3rd option.

1st

First option

1st