多形性回形针与Rails 5一起奇怪地工作

Question

视图：

<div class="kitchen_settings">
<%= form_for @kitchen, :html => { :multipart => true, "data-ajax" => false} do |f| %>
     <%= f.text_field :title,placeholder: "#{current_user.fullname}'s Kitchen", autofocus: true %>
    <%= f.text_field :bio, placeholder: 'something about your kitchen' %>

    <%= f.fields_for :picture do |photo| %>
        <%= photo.file_field :avatar %>
    <% end %>
    <%= f.submit %>
<% end %>

kitchen_controller.rb

class KitchensController < ApplicationController
    before_action :authenticate_user!

    def new
        @kitchen = Kitchen.new
        @kitchen.build_picture
    end

    def create
        @kitchen = current_user.build_kitchen(kitchen_params)
    respond_to do |format|
        if @kitchen.save
          format.html { redirect_to dashboard_path, notice: 'Kitchen was successfully created.' }
          format.json { render :show, status: :created, location: dashboard_path }
        else
          format.html { render :new }
          format.json { render json: @kitchen.errors, status: :unprocessable_entity }
        end
      end
    end

    def show
        @kitchen = Kitchen.find (params[:id])
    end

    private
    def kitchen_params
        params.require(:kitchen).permit(:title,:bio, picture_attributes: [:avatar])
    end
end

kitchen.rb

class Kitchen < ApplicationRecord
  belongs_to :user

  has_one :picture, as: :imageable, dependent: :destroy
  accepts_nested_attributes_for :picture
end

picture.rb

class Picture < ApplicationRecord
    belongs_to :imageable, polymorphic: true

    has_attached_file :avatar, styles: { medium: "300x300>", thumb: "100x100"}, default_url: "/assets/:style/missing.png"
  validates_attachment :avatar, :presence => true,
    :content_type => { :content_type => ["image/jpeg", "image/gif", "image/png"] },
    :size => { :in => 0..500.kilobytes }
end

它给了我这个错误

我想要多态图片模型。我决定处理多态图片关联，但它总是回滚.卡住了。我已经把控制台上的图像附加了。谢谢！！使用binding.pry调试它

Answer 1

在Rails 5中，每当定义belongs_to关联时，在此change.To更改此行为之后，默认情况下需要有关联的记录，我设法这样做了：

picture.rb

class Picture < ApplicationRecord
    belongs_to :imageable, polymorphic: true, optional: true

    has_attached_file :avatar, styles: { medium: "300x300>", thumb: "100x100"}, default_url: "/assets/:style/missing.png"

  validates_attachment :avatar, :presence => true,
    :content_type => { :content_type => ["image/jpeg", "image/gif", "image/png"] },
    :size => { :in => 0..500.kilobytes }
end

Answer 2

imageable在image.rb中的验证存在一个问题

当你把厨房和图像一起储存在一起时，一次就可以了。由于厨房尚未创建，图像的Imageable验证失败。这就是为什么要回滚。

要确认它，可以暂时删除验证。

您需要使用inverse_of来完成这项工作。

在image.rb

belongs_to :imageable, polymorphic: true , inverse_of: :image

在kitchen.rb

has_one :picture, as: :imageable, dependent: :destroy,inverse_of: :imageable

我在这两个关联中都添加了inverse_of。它告诉rails这些关联是相反的，所以如果设置了这些关联，就不要进行查询来获取其他关联。

这样，如果设置任何关联，则其他关联将自动设置，验证不会失败。

这里是一个很好的inverse_of使用博客。