Model:

app/models/group.rb

class Group < ActiveRecord::Base
  has_many :group_members
  has_many :members, :through => :group_members
end

app/models/member.rb

class Member < ActiveRecord::Base
  has_many :group_members
  has_many :groups, :through => :group_members
end

app/models/group_members.rb

class GroupMember < ActiveRecord::Base
  belongs_to :group
  belongs_to :member
end

View:

app/views/groups/new.html.erb

<p class="control-group">
    <%= f.label :name, :class => "control-label" %>
    <p class="controls">
        <%= f.text_field :name, :class => "input-xxlarge" %>
    </p>
</p>




     "control-label" %>
    

    
      
      
    
    

Controller:

app/controller/groups_controller.rb

def new
  @group = Group.new
end

def edit
  @group = Group.find(params[:id])
end

def create
  # How to do?
end

def update
  # How to do?
end

最后在控制器中怎么保存多个成员（members）到数据库？