我对Rails相对较新，并且在Deep端有一点点。 我正在使用预先存在的MSSQL DB在Rails 3中工作，并且必须改进模型才能适应。
我似乎创建了我的模型而没有太多问题，但是却遇到了关联问题。
这是我的两个表格的架构
create_table "ip_addresses", :id => false, :force => true do |t|
t.integer "id", :null => false
t.integer "computer_id", :null => false
t.string "ip", :limit => 64, :null => false
t.string "ip_subnet", :limit => 64, :null => false
t.datetime "timestamp", :null => false
t.datetime "created_at"
t.datetime "updated_at"
end
create_table "computers", :id => false, :force => true do |t|
t.integer "id", :null => false
t.string "uid", :limit => 128
t.string "enclosure_uid", :limit => 128
t.string "name", :limit => 128
t.integer "status_id", :null => false
t.integer "designation_id", :null => false
t.integer "hardware_type_id", :null => false
t.string "hardware_model", :limit => 128
t.string "processor_model", :limit => 128
t.integer "processor_speed"
t.integer "processor_cores_per_proc", :limit => 1
t.integer "processor_count"
t.decimal "memory", :precision => 9, :scale => 2
t.decimal "physical_disk", :precision => 9, :scale => 2
t.integer "san_disk"
t.string "os_name", :limit => 128
t.string "os_version", :limit => 128
t.string "os_patchlevel", :limit => 128
t.integer "campus_id", :null => false
t.text "description"
t.datetime "modification_date", :null => false
t.datetime "os_installdate"
t.datetime "created_at"
t.datetime "updated_at"
end
以下是两个模型
class Computer < ActiveRecord::Base
has_many :ip_addresses
end
class IpAddress < ActiveRecord::Base
belongs_to :computer
end
当我使用IpAddress类时，似乎协会正在工作，但不是来自Computer类。
见下文。
>> IpAddress.first.computer.name
"GC-PRD-PS02"
>> Computer.first.ip_addresses.ip
NoMethodError: undefined method `ip' for #<Class:0x10291cb18>
from /usr/local/lib/ruby/gems/1.8/gems/activerecord-3.0.10/lib/active_record/base.rb:1014:in `method_missing'
from /usr/local/lib/ruby/gems/1.8/gems/activerecord-3.0.10/lib/active_record/associations/association_collection.rb:444:in `send'
from /usr/local/lib/ruby/gems/1.8/gems/activerecord-3.0.10/lib/active_record/associations/association_collection.rb:444:in `method_missing'
from /usr/local/lib/ruby/gems/1.8/gems/activerecord-3.0.10/lib/active_record/base.rb:1127:in `with_scope'
from /usr/local/lib/ruby/gems/1.8/gems/activerecord-3.0.10/lib/active_record/associations/association_proxy.rb:207:in `send'
from /usr/local/lib/ruby/gems/1.8/gems/activerecord-3.0.10/lib/active_record/associations/association_proxy.rb:207:in `with_scope'
from /usr/local/lib/ruby/gems/1.8/gems/activerecord-3.0.10/lib/active_record/associations/association_collection.rb:440:in `method_missing'
from (irb):40
奇怪的是我可以使用
查看IpAddress类的整个行对象>> Computer.first.ip_addresses
[#<IpAddress id: 175, computer_id: 687, ip: "10.0.246.80", ip_subnet: "255.255.255.192", timestamp: "2011-08-03 11:17:57", created_at: "2011-10-07 01:06:16", updated_at: "2011-10-07 01:06:16">, #<IpAddress id: 176, computer_id: 687, ip: "192.168.234.235", ip_subnet: "255.255.255.255", timestamp: "2011-08-03 11:17:57", created_at: "2011-10-07 01:06:16", updated_at: "2011-10-07 01:06:16">, #<IpAddress id: 177, computer_id: 687, ip: "192.168.159.1", ip_subnet: "255.255.255.0", timestamp: "2011-08-03 11:17:57", created_at: "2011-10-07 01:06:16", updated_at: "2011-10-07 01:06:16">, #<IpAddress id: 178, computer_id: 687, ip: "192.168.42.1", ip_subnet: "255.255.255.0", timestamp: "2011-08-03 11:17:57", created_at: "2011-10-07 01:06:16", updated_at: "2011-10-07 01:06:16">]
我已经搜索了很多，试图解决这个问题。我确信这只是我做协会的方式。任何帮助都会得到很多赞赏。
谢谢， 罗布
答案 0 :(得分：4)
由于Computer.first.ip_addresses是一个数组，您需要执行以下操作：
Computer.first.ip_addresses.first.ip
如果你想要拳头ip
Computer.first.ip_addresses.map(&:ip)
如果你想要所有的ips
答案 1 :(得分：1)
在集合上调用ip - 看起来像是问题。 Computer.first.ip_addresses[0].ip应该有用（假设ip_addresses至少包含一个元素）。
另外，对于学习，请注意puts Computer.first.ip_addresses.class给你的内容。