错误:验证失败:必须存在可成像的图像，rails-5.0，paperclip-5 [英] Error: Validation failed: Images imageable must exist , rails-5.0 , paperclip-5

问题描述

当我尝试提交表单时，发生以下错误:Validation failed: Images imageable must exist并呈现相同的new.html.erb视图.

While i was trying to submit the form, following error occured: Validation failed: Images imageable must exist and render the same new.html.erb view.

如果我评论new.html.erb中的file field.产品创建成功.

If i comment the file field in new.html.erb. Product is being created successfully.

ProductsController:

def new
    @product = Product.new
end

def create
    @product = Product.create!(product_params)

    if @product.save
        redirect_to products_path, notice: "Product Created Successfully"
    else
        render "new"
    end
end
def product_params
        params.require(:product).permit(:name, :quantity, :price, images_attributes: [:id, :photo, :_destroy])
end

new.html.erb:

<%= nested_form_for @product, html: { multipart: true } do |f|%>

    <h2>New</h2>

    <P> <%= f.label :name %> <%= f.text_field :name %> </P>
    <P> <%= f.label :quantity %> <%= f.text_field :quantity %> </P>
    <P> <%= f.label :price %> <%= f.text_field :price %> </P>
  <%= f.fields_for :images do |p| %>
    <p> <%= p.label :photo %> <%= p.file_field :photo %> </p>
    <%= p.link_to_remove "Remove Image" %>
  <% end %>
  <%= f.link_to_add "Add Image", :images %>

  <%= f.submit "Add Product" %>
<% end %>

20160725102038_add_image_columns_to_imageable.rb:

class AddImageColumnsToImageable < ActiveRecord::Migration[5.0]

  def up
    add_attachment :images, :photo
  end

  def down
    remove_attachment :images, :photo
  end

end

型号:product.rb

class Product < ApplicationRecord
    has_one :variant
  has_many  :images, as: :imageable,  dependent: :destroy

  accepts_nested_attributes_for :images, allow_destroy: true
end

型号:image.rb

class Image < ApplicationRecord
  belongs_to :imageable, polymorphic: true

  has_attached_file :photo, styles: { medium: "300x300>", thumb: "100x100>" }, default_url: "/images/:style/missing.png"
  validates_attachment :photo, content_type: { content_type: ["image/jpg", "image/jpeg", "image/png", "image/gif"] }

end

推荐答案

在rails 5中，belongs_to确保关联的模型必须存在. 例如，在此多态关联中，图像模型具有belongs_to :imageable，而产品模型具有has_many :images. 因此，在new.html.erb中，我们正在创建图像，但是相应的产品不存在，所以这就是错误Image imageable must exist的原因.

In rails 5, belongs_to makes sure that the associated model must exist. E.g In this polymorphic association, Image model has belongs_to :imageable and Product model has has_many :images. So here in new.html.erb we are creating an image, but respective product not exist, so that's why error Image imageable must exist .

解决方案

在图像模型中关联belong_to时添加optional: true.

Add optional: true while making an association of belong_to in Image model.

图像模型现在看起来像:

Image Model now looks like:

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

  has_attached_file :photo, styles: { medium: "300x300>", thumb: "100x100>" }, default_url: "/images/:style/missing.png"
  validates_attachment :photo, content_type: { content_type: ["image/jpg", "image/jpeg", "image/png", "image/gif"] }

end

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