访问属于另一个模型的模型

Question

我有一个模型'画廊'，它与'Exhbition Images'（并与belongs_to相反）具有'has_many'关系。

我想通过图库模型显示与每个图库相关的图像。但是我遇到的错误

undefined method `exhibition_images' for #<Gallery::ActiveRecord_Relation:0x00000108159dd0> 

当我试图实现这行代码

gallery index: 

<%= @gallery.exhibition_images.each do |exhibition_image| %> 
    <%= exhibition_image.title %> 
<% end %> 

我相信这是很简单的，我失去了一些东西明显。

画廊控制器

def index 
    @gallery = Gallery.all 
end 

画廊模式

class Gallery < ActiveRecord::Base 
    extend FriendlyId 
friendly_id :title, use: :slugged 
belongs_to :guide 
has_many :exhibition_images 
accepts_nested_attributes_for :exhibition_images 
    end 

展览图片

class ExhibitionImage < ActiveRecord::Base 
belongs_to :gallery 

has_attached_file :image, styles: { small: "100x100", guide: "500x500" } 
validates_attachment_content_type :image, :content_type => ["image/jpg", "image/jpeg", "image/png", "image/gif"] 

end 

SCHEMA

create_table "exhibition_images", force: true do |t| 
t.string "image_file_name" 
t.string "image_content_type" 
t.integer "image_file_size" 
t.datetime "image_updated_at" 
t.integer "gallery_id" 
t.datetime "created_at" 
t.datetime "updated_at" 

末

create_table "galleries", force: true do |t| 
t.string "title" 
t.string "slug" 
t.integer "guide_id" 
t.datetime "created_at" 
t.datetime "updated_at" 
end 

Answer 1

undefined method `exhibition_images' for #<Gallery::ActiveRecord_Relation:0x00000108159dd0> 

您正在尝试在一个ActiveRecord::Relation访问exhibition_images。你有关系的对象，因为你美其名曰：

@gallery = Gallery.all 

这就给了你，你可以用它来链接在一起多个查询条件范围。您需要获得一个单独的图库对象才能致电exhibition_images。你可以通过调用@gallery做first这个，或者你需要通过结果来执行查询和迭代：

<%= @gallery.each do |gallery| %> 
    gallery.exhibition_images.each do |exhibition_image| %> 
    <%= exhibition_image.title %> 
    <% end %> 
<% end %> 

如果你这样做，但是，我一定要急于负载exhibition_images：

@gallery = Gallery.includes(:exhibition_images).all 

Answer 2

问题是@gallery包含一个Gallery对象数组。

在你的控制器，你应该有：

@galleries = Gallery.all 

然后遍历数组@galleries

<% for gallery in @galleries %> 
    <%= gallery.exhibition_images.each do |exhibition_image| %> 
    <%= exhibition_image.title %> 
    <% end %> 
<% end %>