Rails 4如何使用载波验证嵌套属性的数量(多个图像/图片)

Question

我是Stackoverflow＆amp;铁轨。我有三种型号，用户，帖子，post_attachment(创建post_attachment脚手架(。我想做的是，每个帖子(帖子的标题，内容，图片(用户只能上传5张图片(我的意思是每个帖子(。我转介本文以实现多个图像，并基本遵循此代码。我还发现了这篇文章来验证Nested_attributes，但只有图片验证(Nested_attributes(无法正常工作。任何想法，将不胜感激。谢谢。

user.rb：

class User < ActiveRecord::Base
   has_many :posts, dependent: :destroy 
end

POST.RB：

class Post < ActiveRecord::Base
   belongs_to :user
   has_many :post_attachments
   accepts_nested_attributes_for :post_attachments,allow_destroy: true, reject_if: :all_blank
end

POST_ATTACHMENT.RB：

class PostAttachment < ActiveRecord::Base
   mount_uploader :picture,PictureUploader 
   belongs_to :post
end

POST_CONTROLLER.RB：

def new
   @post = Post.new
   @post_attachment = @post.post_attachments.build
end
def show
   @post_attachments = @post.post_attachments.all
end
def create
   @post = current_user.posts.build(post_params)
  if @post.save
    params[:post_attachments]['picture'].each do |a|
          @post_attachment = @post.post_attachments.create!(:picture => a, :post_id => @post.id)
    end
    redirect_to @post, notice: "Post Saved" 
   else
     render 'new'
  end
end
private
def post_params
   params.require(:post).permit(:title,:content,:user_id,post_attachments_attributes: [:id, :post_id, :picture, :_destroy])
end

Answer 1

您可以将条件放在create和edit方法之前，也可以将条件放在edit.html.erb中。就像您想节省最多5张照片，可以使用

def create
  @post = current_user.posts.build(post_params)
  if @post.save
    ##@post_attachments = PostAttachment.find_by_post_id(@post.id) --> this can be use in edit
    ##if params[:post_attachments]['picture'].length+ @post_attachment.length <= 5
     if params[:post_attachments]['picture'].length <= 5
       params[:post_attachments]['picture'].each do |a|
          @post_attachment = @post.post_attachments.create!(:picture => a, :post_id => @post.id)
       end
     elsif params[:post_attachments]['picture'].length > 5
       flash[:error] = 'Your message'
       redirect_to YOUR_PATH
       return false
     end
     redirect_to @post, notice: "Post Saved" 
  else
   if params[:post_attachments]['picture'].length > 5
      @post.errors[:base] << "Maximuim 5 messages/pictures."
   end
   render 'new'
 end
end

还可以在编辑帖子时查看中的查看。

<% if @post_attachments.length <= 5 %>
   <%= f.file_field %>
<% end %>