Rails 4 Attendance system - ruby-on-rails

Question

Hi I'm actually struggling with building a Rails 4 application implementing an attendance model on rails 4, I found maybe two question on stackoverflow but they're posted in 2012 and it failed when i tried following them.
This is the closest one i got on stackoverflow
Edit: I already have a view of classroom and list out the students. And could assign students into the classroom but the problem would be to GET the students into a new attsheet and saving them into attendance
Here's what I currently have now
# Attendance
# take student as a single entry for :attsheet and
# has a :attended (boolean) and remarks as well
class Attendance < ActiveRecord::Base
belongs_to :student
belongs_to :attsheet
end
#Attsheet which means attendance sheet
#has :post_date and :remark
class Attsheet < ActiveRecord::Base
belongs_to :classroom
has_many :attendances
accepts_nested_attributes_for :attendances
end
class Student < ActiveRecord::Base
belongs_to :school
has_and_belongs_to_many :classrooms
has_many :attendances
end
class Classroom < ActiveRecord::Base
belongs_to :school
has_and_belongs_to_many :students
has_many :attsheets
validates :class_name, presence: true
end
I want the classroom to be able to create a new attendance or view attendance archives for each student.
I am able to do this in classroom right now but I'm stuck at what to do next for the controller and view
$ = link_to "New Attendance", new_school_classroom_attsheet_path(#school, #classroom, #attsheet)

Answer 1

In attandances_controller,
class AttendancesController < ApplicationController
before_filter :set_parents
def new
#attendance= #classroom.attendances.new
end
def create
#attendance= #classroom.attendances.new(params[:milestone])
if #attendance.save
redirect_to ....
else
render :action=>:new
end
end
def set_parents
#school= School.find(params[:school_id])
#classroom= #school.classrooms.find(params[:classroom_id])
end
end
and in _form.html.erb of attendacen,
<%= form_for(#school, #classroom, #attendance]) do |f|%>
<% if #attendance.errors.present? %>
<ul class="warning">
<% #attendance.errors.full_messages.each do |message| %>
<li><%= message%></li>
<% end %>
</ul>
<% end %>
<h2>Attendance</h2>
.........
<%= f.submit button %>
<% end %>
this will submit fotm to create action of attendance

Answer 2

I found the solution by doing
I changed attsheet to attendance_list
def new
#attendance_list = #classroom.attendance_lists.new
#attendance_list.attendances = #classroom.student_ids.map do |student_id|
#attendance_list.attendances.build(student_id: student_id)
end
end
def create
#attendance_list = #classroom.attendance_lists.new(attendance_list_params)
#attendance_list.classroom_id = params[:classroom_id]
respond_to do |format|
if #attendance_list.save
format.html {redirect_to school_classroom_path(#school, #classroom), notice: "You added the attendance!" }
else
redirect_to new_school_attendance_list_path(attendance_list_params)
end
end
end
with simple fields
= f.simple_fields_for :attendances do |g|
= g.input :student_id, as: :hidden
...... more fields ...