我想要做的是让用户选择至少一张图片（最多3张图片）并在\ views \ shared \ _article_form.html.erb中输入f.text_area :content。
我在\ models \ article.rb中添加了自定义验证check_for_at_least_image
它仅在create操作中有效（仅显示错误消息），但它在update操作中无效。
如何在update操作中检查无图像并显示错误消息。
article有很多photo。
日志如下。
\ log / development.log
新创建时无图像（错误消息按我的预期显示）
Started POST "/articles" for 127.0.0.1 at 2014-09-13 10:40:49 +0900
Processing by ArticlesController#create as HTML
Parameters: {"utf8"=>"笨・, "authenticity_token"=>"xxxx=", "article"=>{"category_id"=>"1379", "photos_attributes"=>{"0"=>{"article_id"=>""}, "1"=>{"article_id"=>""}, "2"=>{"article_id"=>""}}, "content"=>"test"}, "commit"=>"逋ｻ骭ｲ縺吶ｋ"}
[1m[35mUser Load (0.0ms)[0m SELECT "users".* FROM "users" WHERE "users"."remember_token" = 'xxxx' LIMIT 1
[1m[36m (0.0ms)[0m [1mbegin transaction[0m
[1m[35m (0.0ms)[0m rollback transaction
[1m[36mCategory Load (1.0ms)[0m [1mSELECT "categories".* FROM "categories" WHERE "categories"."id" = ? LIMIT 1[0m [["id", 1379]]
Rendered shared/_error_messages.html.erb (1.0ms)
Rendered shared/_article_form.html.erb (8.0ms)
Rendered articles/new.html.erb within layouts/application (10.0ms)
Rendered layouts/_header.html.erb (1.0ms)
Rendered layouts/_footer.html.erb (0.0ms)
Completed 200 OK in 63ms (Views: 51.0ms | ActiveRecord: 1.0ms)
删除所有（三张）图片（未显示错误讯息）
Started PATCH "/articles/40" for 127.0.0.1 at 2014-09-13 11:10:00 +0900
Processing by ArticlesController#update as HTML
Parameters: {"utf8"=>"笨・, "authenticity_token"=>"xxxx=", "article"=>{"category_id"=>"1379", "photos_attributes"=>{"0"=>{"article_id"=>"40", "_destroy"=>"1", "id"=>"132"}, "1"=>{"article_id"=>"40", "_destroy"=>"1", "id"=>"133"}, "2"=>{"article_id"=>"40", "_destroy"=>"1", "id"=>"134"}}, "content"=>"test"}, "commit"=>"譖ｴ譁ｰ縺吶ｋ", "id"=>"40"}
[1m[35mUser Load (0.0ms)[0m SELECT "users".* FROM "users" WHERE "users"."remember_token" = 'xxxx' LIMIT 1
[1m[36mArticle Load (0.0ms)[0m [1mSELECT "articles".* FROM "articles" WHERE "articles"."user_id" = ? AND "articles"."id" = 40 ORDER BY created_at DESC LIMIT 1[0m [["user_id", 1]]
[1m[35mArticle Load (1.0ms)[0m SELECT "articles".* FROM "articles" WHERE "articles"."id" = ? ORDER BY created_at DESC LIMIT 1 [["id", "40"]]
[1m[36m (0.0ms)[0m [1mbegin transaction[0m
[1m[35mPhoto Load (1.0ms)[0m SELECT "photos".* FROM "photos" WHERE "photos"."article_id" = ? AND "photos"."id" IN (132, 133, 134) [["article_id", 40]]
[1m[36m (0.0ms)[0m [1mSELECT COUNT(*) FROM "photos" WHERE "photos"."article_id" = ?[0m [["article_id", 40]]
[1m[35mSQL (1.0ms)[0m DELETE FROM "photos" WHERE "photos"."id" = ? [["id", 132]]
[1m[36mSQL (0.0ms)[0m [1mDELETE FROM "photos" WHERE "photos"."id" = ?[0m [["id", 133]]
[1m[35mSQL (0.0ms)[0m DELETE FROM "photos" WHERE "photos"."id" = ? [["id", 134]]
[1m[36m (4.0ms)[0m [1mcommit transaction[0m
Redirected to http://localhost:3000/users/1
Completed 302 Found in 26ms (ActiveRecord: 7.0ms)
照片表
sqlite> .schema photos
CREATE TABLE "photos" ("id" INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL, "articl_id" integer, "image" varchar(255), "created_at" datetime, "updated_at" datetim);
\模型\ article.rb
# encoding: utf-8
class Article < ActiveRecord::Base
belongs_to :user
belongs_to :category
has_many :photos, dependent: :destroy
accepts_nested_attributes_for :photos, reject_if: :all_blank, allow_destroy: true
default_scope -> { order('created_at DESC') }
validates :content, presence: true, length: { maximum: 140 }
validates :user_id, presence: true
validates :category_id, presence: true
validate :check_for_at_least_image
def build_images
(3 - self.photos.size).times {self.photos.build}
end
def check_for_at_least_image
errors.add(:image, "select...") if self.photos.size <= 0
end
end
\模型\ photo.rb
class Photo < ActiveRecord::Base
belongs_to :article
mount_uploader :image, ImageUploader
end
\视图\物品\ edit.html.erb
<div class="row">
<div class="span8">
<%= render 'shared/article_form' %>
</div>
</div>
\ view \ shared \ _article_form.html.erb
<%= form_for(@article) do |f| %>
<%= render 'shared/error_messages', object: f.object %>
<div class="field">
<%= f.hidden_field :category_id %>
<%= f.fields_for :photos do |p| %>
<%= p.hidden_field :article_id %>
<div class="photo">
<% if p.object.image and p.object.image.file %>
<%= image_tag p.object.image.thumb.url %>
<p>article:<%= @article.id %></p>
<p>photo:<%= p.object.id %></p>
<%= p.hidden_field :image_cache if p.object.image_cache %>
<label><%= p.check_box :_destroy %>delete</label>
<% end %>
<%= p.file_field :image %>
</div>
<% end %>
<%= f.text_area :content, placeholder: "Enter content..." %>
</div>
<%= f.submit class: "btn btn-large btn-primary" %>
<% end %>
\控制器\ articles_controller.rb
class ArticlesController < ApplicationController
before_action :signed_in_user, only: [:create, :destroy]
before_action :correct_user, only: [:update, :destroy]
.
.
def new
@article = Article.new
@category = Category.find(params[:category])
@article.category_id = @category.id
3.times { @article.photos.build }
end
def create
@article = current_user.articles.build(article_params)
if @article.save
flash[:success] = "article created!"
redirect_to current_user #root_url
else
@article.build_images
render 'new'
end
end
.
.
def edit
@article = Article.find(params[:id])
@article.build_images
end
def update
@article = Article.find(params[:id])
if @article.update(article_params)
redirect_to current_user
else
render 'edit'
end
end
def destroy
@article.destroy
redirect_to root_url
end
private
def article_params
params.require(:article).permit(:content, :category_id, photos_attributes: [:id, :article_id, :image, :image_cache, :_destroy])
end
.
.
end
答案 0 :(得分：0)
只是查看了你的问题，并且 认为可能是你的验证在儿童对象的破坏性调用之前运行 并进行了一些搜索并找到了{{3}看起来我认为在毁灭之前运行验证是正确的。只是发布与您的问题相关的指针
这里的问题是在验证父对象之后，accept_nested_attributes_for为子对象调用destroy。因此用户可以删除图像。当然，稍后，当用户尝试编辑文章时，他/她将收到错误 - “选择至少一个图像。”。
<强>修正：
accepts_nested_attributes_for :photos, reject_if: proc { |attributes| attributes['image'].blank? } , allow_destroy: true #as discussed in your other question you have to use proc to solve your update problem
validate :check_for_at_least_image
def check_for_at_least_image
errors.add(:image, "select...") if photos.reject(&:marked_for_destruction?).size <= 0
end