错误：undefined method `options' for #Mongoid::Relations::Metadata:0x00000003742388
基于 mongoid
在 User 模型中
has_and_belongs_to_many :group
在 Group 模型中
has_and_belongs_to_many :user
表单视图
<%= simple_form_for(@group) do |f| %>
<% if @group.errors.any? %>
<div id="error_explanation">
<h2><%= pluralize(@group.errors.count, "error") %> prohibited this group from being saved:</h2>
<ul>
<% @group.errors.full_messages.each do |msg| %>
<li><%= msg %></li>
<% end %>
</ul>
</div>
<% end %>
<%= f.label :name, :label => '名称' %>
<%= f.input_field :name %>
<%= f.association :user %>
<%= f.button :submit, :value => '创建用户组' %>
<% end %>
出错在这一句
<%= f.association :user %>
console 里关联关系无异常
Reloading...
=> true
irb(main):097:0> u=User.new
=> #<User _id: 4ef1bd5d53cd2108dd000008, _type: nil, created_at: nil, updated_at: nil, name: nil, email: nil, mobile: nil, tel: nil, alias: nil, birthday: nil, second_email: nil, address: nil, company: nil, memo: nil, plan_ids: [], group_ids: []>
irb(main):098:0> g=Group.new
=> #<Group _id: 4ef1bd6753cd2108dd000009, _type: nil, created_at: nil, updated_at: nil, name: nil, user_ids: []>
irb(main):099:0> u.group << g
=> []
irb(main):100:0> u.group
=> [#<Group _id: 4ef1bd6753cd2108dd000009, _type: nil, created_at: nil, updated_at: nil, name: nil, user_ids: [BSON::ObjectId('4ef1bd5d53cd2108dd000008')]>]
irb(main):101:0> g
=> #<Group _id: 4ef1bd6753cd2108dd000009, _type: nil, created_at: nil, updated_at: nil, name: nil, user_ids: [BSON::ObjectId('4ef1bd5d53cd2108dd000008')]>
irb(main):102:0>
没遇到过。。。先试试单纯的 user belongs_to group 试试？ 或者你可以试着看看 simple_form 里有关 association 的代码 https://github.com/plataformatec/simple_form/blob/master/lib/simple_form/form_builder.rb
