Can we manually add one entry into dynamic drop down list, If then how in Ruby On Rails -

i have student, student_parent , address_detail table want add student , it's parent(father , mother) address in address_detail table, have folowing relation between tables

student:- has_many :student_parents has_many :address_details

student_parent: belongs_to :student has_many :address_detail

address_detail: belongs_to :student belongs_to :student_parent

in address_detail form have drop down father , mother want add student entry manually how can do, here my address_detail form``

    <%= simple_form_for @address_detail, :html => { :class => 'form-horizontal' } |f| %> <div class="control-group">   <label  class = "control-label"> address correspond <abbr title="required">*</abbr></label>   <div class="controls">     <%= f.collection_select(:student_parent_id, student_parent_relation_collection , :id, :relation_to_student, {:prompt => true}, :required =>true  )%>     <%= f.hidden_field :student_id, :value => current_student_id %>   </div> </div> 

.... .....

here helper method address_correspond_to drop down method

# return collection of parent relation student 

def student_parent_relation_collection

if current_user != nil   student =  student.find_all_by_user_id(current_user.id)   logger.info "student_is = #{student}"   if student != nil   return  studentparent.find_all_by_student_id(student)  end end 

end

current output father mother

i want out student father mother

class addressdetail < activerecord::base    def student_and_parents     [student, student_parent]   end  end 

then, in view can either refer

address_detail.student_and_parents 

or in user

class user < activerecord::base    has_many :students   has_many :student_parents, :through => :students    def students_and_parents     [students, student_parents].compact.flatten   end  end 

you can refer

current_user.try(:students_and_parents)