ruby-on-rails – 接受has_many关系的嵌套属性

class Patient < ActiveRecord::Base
  belongs_to :user,:dependent => :destroy
  has_many :enrollments,:dependent => :destroy
  has_many :clients,:through => :enrollments

  accepts_nested_attributes_for :user
  accepts_nested_attributes_for :enrollments
  attr_accessible :user_attributes,:enrollments_attributes,:insurance
end

class Enrollment < ActiveRecord::Base
  belongs_to :client
  belongs_to :patient
  attr_accessible :client_id,:patient_id,:active 
end

在我的患者表格中,我希望有一个多选框,可以将患者分配给客户.有没有办法可以做到这一点,所以我没有任何逻辑
控制器除外

@patient = Patient.new(params)
@patient.save

我试过这个：

<%= patient_form.fields_for :enrollments do |enrollments_fields| %>
<tr>
    <td class="label">
        <%= enrollments_fields.label :client_id %>:                     
    </td>
    <td class="input">
        <%= enrollments_fields.collection_select(:client_id,@clients,:id,:name,{},:multiple => true) %>
    </td>                   
</tr>
<% end %>

但它只保存了第一个客户端.如果我删除多个部分,它的功能,但我只能选择1个客户端！

select的html值是：