Question

我们只是弄清楚Rails 4中多态关系是如何工作的，但我们面临一个小问题，因为关系总是创建一个新的条目，而不是更新现有的关系。

为什么更新多态关系会创建一个新条目而不是更新现有条目？

f.e。用图片类......

图片模型

class Picture < ActiveRecord::Base
  belongs_to :picable, polymorphic: true
end

商店模式

class Shop < ActiveRecord::Base
  has_one :picture, :as => :picable
  accepts_nested_attributes_for :picture
end

表格

  <%= f.fields_for :picture_attributes, @admin_shop.picture||Picture.new do |ff| %>
      <div class="field">
        <%= ff.label :url %><br />
        <%= ff.text_field :url %>
      </div>
  <% end %>

控制器

  def new
    @admin_shop = Shop.new
  end

  # GET /admin/shops/1/edit
  def edit
  end

  # POST /admin/shops
  # POST /admin/shops.json
  def create
    @admin_shop = Shop.new(admin_shop_params)

    respond_to do |format|
      if @admin_shop.save
        format.html { redirect_to admin_shops_url, notice: 'Shop was successfully created.' }
      else
        format.html { render action: 'new' }          
      end
    end
  end

  def update
    respond_to do |format|
      if @admin_shop.update(admin_shop_params)
        format.html { redirect_to admin_shops_url, notice: 'Shop was successfully updated.' }
      else
        format.html { render action: 'edit' }
      end
    end
  end

Answer 1

将：id添加到控制器中params方法的：picture_attributes部分。这几乎肯定会奏效。另一种方法是添加到accepts_nested_attributes_for：

accepts_nested_attributes_for :picture, :update_only => true

Polymorphic Association不会更新，但会创建新条目

1 个答案: