Ruby on Rails:如何连接两个表 [英] Ruby on Rails: How to join two tables

问题描述

我有一个索引页面，我想显示所有用户的个人资料及其相关照片.我正在为照片使用插件 Paperclip.在 Profiles 控制器中，我有实例变量 @profile 但它仅向我显示配置文件表中的表，而不是照片表.

I have an index page that I want to show all the users' profile and their associated photos. I'm using the plugin Paperclip for the photos. In the Profiles controller, I have the instance variable @profile but it shows me the table in the profiles table only and not the photos table.

@profile = Profile.find(:all, :include => :photos,
  :joins => "INNER JOIN photos ON photos.profile_id = profiles.id")

模型如下:

class Profile < ActiveRecord::Base
  has_many :photos
end

class Photo < ActiveRecord::Base
  belongs_to :profile
end

我希望能够在视图中显示的内容类似于:

What I want to be able to show in the View is something like:

• John 的个人资料(例如姓名、年龄、性别)- John 的照片(例如，只显示了一张照片)
• 此处是玛丽的个人资料 - 此处显示的是玛丽的照片
• 此处是鲍勃的个人资料 - 此处显示的是鲍勃的照片

推荐答案

我已经编辑了我的答案以反映您的额外评论.

I've edited my answer to reflect your extra comments.

首先，您不应该需要 :joins 参数；<代码>:include =>:photos 应该为你处理幕后"的加入.

First of all, you shouldn't need the :joins parameter; :include => :photos should handle the join "behind the scenes" for you.

这里有一种方法可以满足您的要求.

Here's one way to do what you're asking about.

(在模型中)

class Profile < ActiveRecord::Base
  has_many :photos
  has_one :primary_photo, :class_name => "Photo", :conditions => {:primary => true}
end

(在控制器中)

@profiles = Profile.find(:all, :include => :primary_photo)

(在视图中)

<% @profiles.each do |profile| %>
  Name: <%= profile.name %>
  Age: <%= profile.age %>
  Photo: <%= image_tag profile.primary_photo.url %>
<% end %>

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