Rails 3 - saving model which belongs_to few models via nested attributes - ruby-on-rails

Question

I have few models - User, Teacher and TeacherLeader.
class User < ActiveRecord::Base
attr_accessor :password
attr_accessible :user_login,
:password,
:teacher_attributes,
:teacher_leader_attributes
has_one :teacher
has_one :teacher_leader
accepts_nested_attributes_for :teacher_leader
end
class Teacher < ActiveRecord::Base
belongs_to :user
has_one :teacher_leader
end
class TeacherLeader < ActiveRecord::Base
belongs_to :user
belongs_to :teacher
end
I want to save data in TeacherLeader via nested attributes. So, in User model i added accepts_nested_attributes_for :teacher_leader and attr_accessible :teacher_leader_attributes.
Also i have controller:
class TeacherLeadersController < ApplicationController
def new
...
#user = User.new
#teacher_leader = #user.build_teacher_leader
#teachers_collection = Teacher.all
.collect do |t|
[ "#{t.teacher_last_name} #{t.teacher_first_name} #{t.teacher_middle_name}", t.id ]
end
#choosen_teacher = #teachers_collection.first.last unless #teachers_collection.empty?
end
def create
user = User.new( params )
user.user_role = "class_head"
if user.save
flash[:success] = "Successfully created class head!"
else
flash[:error] = user.errors.full_messages
end
end
end
Also i i have view for TeacherLeader controller (new.html.erb):
<%= form_for #user, :url => teacher_leaders_url, :html => {:class => "form-horizontal"} do |f| %>
<%= field_set_tag do %>
<%= f.fields_for :teacher_leader do |tl| %>
<div class="control-group">
<%= tl.label :teacher_id, "Teacher names", :class => "control-label" %>
<div class="controls">
<%= select_tag( :teacher_id,
options_for_select( #teachers_collection, #choosen_teacher )) %>
</div>
</div>
<% end %>
<div class="control-group">
<%= f.label :user_login, "Login", :class => "control-label" %>
<div class="controls">
<%= f.text_field :user_login %>
</div>
</div>
<div class="control-group">
<%= f.label :password, "Pass", :class => "control-label" %>
<div class="controls">
<%= f.text_field :password %>
</div>
</div>
<% end %>
<%= f.submit "Create", :class => "btn btn-large btn-success" %>
When i'm trying to save my models, i get strange errors such "User login can't be empty" and others. I know that validations of User models generate them (i don't know why, i get such errors even if have values in params). I suppose, that i do something wrong in view, because after submiting i have such params:
teacher_id: '1'
user: !ruby/hash:ActiveSupport::HashWithIndifferentAccess
user_login: schoolh_1rF32
password: txaqxuTXz96auhX
commit: Create
action: create
controller: teacher_leaders
But i should have something like this:
user: !ruby/hash:ActiveSupport::HashWithIndifferentAccess
user_login: schoolh_1rF32
password: txaqxuTXz96auhX
teacher_leader_attributes:
teacher_id: '1'
What is wrong? Can i fix that?
UPD: HTML code for class head creation page:
<form accept-charset="UTF-8" action="http://0.0.0.0:3000/teacher_leaders" class="form-horizontal" id="new_user" method="post"><div style="margin:0;padding:0;display:inline"><input name="utf8" type="hidden" value="✓" /><input name="authenticity_token" type="hidden" value="ZKlDTKG8SU8fZuMrUfQoCOSGknOhj651DT2LJDrfliA=" /></div>
<fieldset>
<div class="control-group">
<label class="control-label" for="user_teacher_leader_attributes_teacher_id">Teacher names</label>
<div class="controls">
<select id="teacher_id" name="teacher_id">
<option value="1" selected="selected">Jack P. Tompson </option>
<option value="2">Ronald V. Herwud</option>
</div>
</div>
<div class="control-group">
<label class="control-label" for="user_user_login">Login</label>
<div class="controls">
<input id="user_user_login" name="user[user_login]" size="30" type="text" />
</div>
</div>
<div class="control-group">
<label class="control-label" for="user_password">Password</label>
<div class="controls">
<input id="user_password" name="user[password]" size="30" type="text" />
</div>
</div>
</fieldset>
<input class="btn btn-large btn-success" name="commit" type="submit" value="Create" />
</form>

Answer 1

You need not
<%= select_tag( :teacher_id,
options_for_select( #teachers_collection, #choosen_teacher )) %>
but something like
<%= tl.select( :teacher_id,
options_for_select( #teachers_collection, #choosen_teacher )) %>