Activeadmin formtastic dynamiki wybrać

Question

Chciałbym, aby wybrać opcję dynamicznego poprzez formtastic Activeadmin jest tak:

form do |f| 
    f.inputs "Exam Registration Details" do 
     f.input :user_id, :as => :select, :collection => User.where(:admin => 'false') 
     #selects user from list. WORKING 

     f.input :student_id, :as => :select, :collection => Student.joins(lessons: :user) 
     #collection of students will change to students who have lessons with chosen user. NOT WORKING, returns all students who have lessons. 

     f.input :lesson_id, :as => :select, :collection => Lesson.joins(:student, :user) 
     #collection of lessons will change to reflect lessons connected by chosen user and student. NOT WORKING, returns all lessons. 
    end 
    f.buttons 
    end 

Mój kod amatorski jest oczywiście nie działa tak jak zamierzałem go. Jakie zmiany powinienem wprowadzić?

mam 4 modele jak poniżej:

class Student < ActiveRecord::Base 
    has_many :lessons 
    has_many :users, through: :lessons 
    has_many :exam_registrations, through: :lessons 

class Lesson < ActiveRecord::Base 
    belongs_to :user 
    belongs_to :student 
    belongs_to :exam_registration 

class User < ActiveRecord::Base 
    has_many :lessons 
    has_many :students, through: :lessons 
    has_many :exam_registrations, through: :lessons 

class ExamRegistration < ActiveRecord::Base 
    has_many :lessons 
    has_many :users, through: :lessons 
    has_many :students, through: :lessons 

Answer 1

SOLVED

dla nikogo innego Zapasy z tym samym problemem, spojrzeć na ten railscast

oto jak I wdrożone wiele dynamicznych wybierz menu w activeadmin :

config/initializers/active_admin.rb

config.register_javascript 'exam_registrations.js.coffee' 

app/admin/exam_registrations.rb

form do |f| 
    f.inputs "Exam Registration Details" do 
     f.input :user_id, :label => 'Teacher', :as => :select, :collection => User.where(:admin => 'false', :active => true).order(:name), :include_blank => true 
     f.input :student_id, :hint => 'Students grouped by teacher names', :as => :select, :collection => option_groups_from_collection_for_select(User.where(:admin => false, :active => true).order(:name), :students, :name, :id, :name) 
     f.input :lesson_id, :hint => 'Lessons grouped by student names', :as => :select, :collection => option_groups_from_collection_for_select(Student.where(:active => true).order(:name), :lessons, :name, :id, :name) 
    end 
    f.buttons 
    end 

app/assets/javascripts/exam_registrations.js.coffee

#first menu  
jQuery -> 
     $('#exam_registration_student_id').parent().hide() 
     students = $('#exam_registration_student_id').html() 
     $('#exam_registration_user_id').change -> 
     user = $('#exam_registration_user_id :selected').text() 
     escaped_user = user.replace(/([ #;&,.+*~\':"!^$[\]()=>|\/@])/g, '\\$1') 
     options = $(students).filter("optgroup[label='#{escaped_user}']").html() 
     if options 
      $('#exam_registration_student_id').html(options) 
      $('#exam_registration_student_id').parent().show() 
     else 
      $('#exam_registration_student_id').empty() 
      $('#exam_registration_lesson_id').empty() 

# second menu 
    $('#exam_registration_lesson_id').parent().hide() 
    lessons = $('#exam_registration_lesson_id').html() 
    $('#exam_registration_student_id').click -> 
    student = $('#exam_registration_student_id :selected').text() 
    escaped_student = student.replace(/([ #;&,.+*~\':"!^$[\]()=>|\/@])/g, '\\$1') 
    options = $(lessons).filter("optgroup[label='#{escaped_student}']").html() 
    if options 
     $('#exam_registration_lesson_id').html(options) 
     $('#exam_registration_lesson_id').parent().show() 
    else 
     $('#exam_registration_lesson_id').empty() 

restart serwera i menu praca !