ruby-on-rails – Rails集合选择表格不保存HABTM协会

形成

<%= form_for @entry do |f| %>
  <% if @entry.errors.any? %>
    <div id="error_explanation">
      <h2><%= pluralize(@entry.errors.count,"error") %> prohibited this entry from being saved:</h2>

      <ul>
      <% @entry.errors.full_messages.each do |msg| %>
        <li><%= msg %></li>
      <% end %>
      </ul>
    </div>
  <% end %>

  <div class="field">
    <%= f.label :content %><br>
    <%= f.text_area :content %>
  </div>

  <div class="field">
    <%= f.label :category_ids,"Categories" %><br />
    <%= f.collection_select :category_ids,Category.order(:name),:id,:name,{},{multiple: true} %>
  </div>

  <div class="actions">
    <%= f.submit 'Submit' %>
  </div>
<% end %>

强参数

private
    def entry_params
        params.require(:entry).permit(:content,:category_ids)
    end

进入模式

class Entry < ActiveRecord::Base
  belongs_to :user
  has_and_belongs_to_many :categories

  validates :content,:user_id,presence: true
end

分类模型

class Category < ActiveRecord::Base
  belongs_to :user
  has_and_belongs_to_many :entries
end

加入表格

class EntriesCategories < ActiveRecord::Base
    belongs_to :entry
    belongs_to :categories
end