Question

Newbie Rails问题......我知道有更好的方法来做到这一点。我需要帮助理解为什么这不像我认为的那样工作。我正在使用与现有数据库的“has_many”关系进行简单的连接表。我需要保持“非铁路”友好的头衔。

这是输出＆lt;％= room.levels％＆gt;如浏览器中所示：[#<Level Name: "01 - FIRST FLOOR">] 我想在没有所有其他信息的情况下只看到01 - FIRST FLOOR。

我有两张桌子。：房间和：水平

这是两个表的架构：

create_table "levels", :primary_key => "Id", :force => true do |t|
t.integer "TypeId"
t.integer "DesignOption"
t.string  "Name"
t.float   "Elevation"

create_table "rooms", :primary_key => "Id", :force => true do |t|
t.integer "DesignOption"
t.integer "PhaseId"
t.string  "Comments"
t.float   "Volume"
t.float   "Perimeter"
t.integer "Level"
t.string  "Occupancy"
t.float   "Area"
t.string  "Number"
t.string  "Name"
end

 add_index "rooms", ["Id"], :name => "Id", :unique => true

这是app / model / room.rb：

class Room < ActiveRecord::Base
   attr_accessible :Area, :Level, :Name, :Number, :Perimeter, :PhaseId, :Elevation
   has_many :levels, :primary_key => 'Level', :foreign_key => 'Id', :select => 'Name' set_primary_key :Id
end

以下是app / views / rooms / index.html.erb的摘录：

<% @rooms.each do |room| %>
  <tr>
    <td><%= room.Name %></td>
    <td><%= room.Number %></td>
    <td><%= room.PhaseId %></td>
    <td><%= room.levels %></td>
    <td><%= link_to 'Show', room %></td>
    <td><%= link_to 'Edit', edit_room_path(room) %></td>
    <td><%= link_to 'Destroy', room, method: :delete, data: { confirm: 'Are you sure?' } %></td>
  </tr>

谢谢！

Answer 1

你可以这样做：

<td><%= room.levels.map(&:Name).join(', ') %></td>

为什么您的代码无法正常工作？因为room.levels返回一个Level对象数组。您需要遍历它们以获取每个名称，然后显示它。

room.levels
# => returns all the level objects associated

room.levels.map(&:Name)
# => collect each name of the level objects (makes an array of (String) names)

room.levels.map(&:Name).join(', ')
# => Return a nice String with all the levels name with ", " between each.

Answer 2

因为levels会为您提供回收。你需要迭代room.levels并在那里获得元素

Answer 3

对于你当前的Schema，Room belongs_to级别，房间没有办法可以有多个级别（除非只有那两个表）

create_table "rooms", :primary_key => "Id", :force => true do |t|
...
t.integer "Level" # One-to-One relation

所以，你需要的是：

# Model
class Room < ActiveRecord::Base
   attr_accessible :Area, :Level, :Name, :Number, :Perimeter, :PhaseId, :Elevation
   belongs_to :level, :primary_key => 'Level', :foreign_key => 'Id', :select => 'Name'

end

# View
<td><%= room.level.name %></td>

has_many加入显示问题

3 个答案: