How to update multiple records with rails 4 & mongoid - ruby-on-rails

Question

I want to model student's attendance, i am following railscast.com/165-edit-multiple-revised i follow Ryan's first approach and try to use it with mongoid. My modified code is as follows but it does not update multple records, well it even doesnt update any of the record. sounds like mongoid does not found any Student with id of an array. plz see the code and let me know what i am doing wrong.
# config/routes.rb
resources :students do
collection do
put :attendance
end
end
# model/student.rb
class Student
include Mongoid::Document
field :name, type: String
field :present, type: Mongoid::Boolean
end
# controllers/students_controller.rb
def attendance
Student.where(id: params[:student_ids]).update_all(present: true)
redirect_to students_url
end
# views/students/index.html.erb
<% #students.each do |student| %>
<tr>
<td><%= check_box_tag "student_ids[]" , student.id %></td>
<td><%= student.name %></td>
<td><%= student.present %></td>
<td><%= link_to 'Show', student %></td>
<td><%= link_to 'Edit', edit_student_path(student) %></td>
<td><%= link_to 'Destroy', student, method: :delete, data: { confirm: 'Are you sure?' } %></td>
</tr>
<% end %>
if i change the code in controller as follows than it works but i am not satisfied with this code. is there any other way around or i am doing something wrong?
# controllers/students_controller.rb
def attendance
params[:student_ids].each do |student_id|
Student.where(id: student_id).update_all(present: true)
end
redirect_to students_url
end

Answer 1

If you want to fetch a set of student, you should try the in operator. Try this:
def attendance
Student.where(:id.in => params[:student_ids]).update_all(present: true)
redirect_to students_url
end
What do you think?