heliang7 (HeLiang)

出二手 iMac（武汉）

heliang7 — Wed, 11 Feb 2015 10:30:49 +0800

帮一个妹子转的。

imac 27 标配，2013 年 7 月入手的，保养良好。

标价 10k，可以小刀，QQ635961048

27 英寸
3.2GHz 四核 Intel Core i5 处理器
Turbo Boost 高达 3.6GHz
8GB (2 个 4GB) 内存
1TB 硬盘 1
NVIDIA GeForce GT 755M 图形处理器，配备 1GB 显存

有武汉的朋友想要的，请 qq 联系。

脚本中使用 active record 的问题

heliang7 — Mon, 17 Feb 2014 17:19:47 +0800

代码如下

require 'active_record'
#require 'activerecord-jdbc-adapter'
require 'activerecord-jdbcmssql-adapter'
require 'logger'
require 'D:\\lib\\jdbc-dirver\\mssql\\sqljdbc.jar'

ActiveRecord::Base.logger = Logger.new(STDOUT)
ActiveRecord::Base.establish_connection(
  adapter:  'sqlserver',
  host:     'localhost',
  username: 'sa',
  password: 'sa',
  database: 'DB'
)

class FormDefine < ActiveRecord::Base
    self.table_name = 'FormDefineTab'
    self.primary_key = 'id'
end

p FormDefine.first(20).to_a

总是最后一行出问题，但是通过 STDOUT 的 logger 可以看到 sql 语句已经执行了（或者生成）错误如下：

NoMethodError: undefined method `attribute_method_matcher' for 0:Fixnum
                 __send__ at org/jruby/RubyBasicObject.java:1709
                     send at org/jruby/RubyKernel.java:2213
  match_attribute_method? at d:/installed/Develop/Java/jruby-1.7.4/lib/ruby/gems
/shared/gems/activemodel-3.2.13/lib/active_model/attribute_methods.rb:444
              respond_to? at d:/installed/Develop/Java/jruby-1.7.4/lib/ruby/gems
/shared/gems/activemodel-3.2.13/lib/active_model/attribute_methods.rb:431
              respond_to? at d:/installed/Develop/Java/jruby-1.7.4/lib/ruby/gems
/shared/gems/activerecord-3.2.13/lib/active_record/attribute_methods.rb:169
           __run_callback at d:/installed/Develop/Java/jruby-1.7.4/lib/ruby/gems
/shared/gems/activesupport-3.2.13/lib/active_support/callbacks.rb:398
      _run_find_callbacks at d:/installed/Develop/Java/jruby-1.7.4/lib/ruby/gems
/shared/gems/activesupport-3.2.13/lib/active_support/callbacks.rb:390
                 __send__ at org/jruby/RubyBasicObject.java:1703
                     send at org/jruby/RubyKernel.java:2209
            run_callbacks at d:/installed/Develop/Java/jruby-1.7.4/lib/ruby/gems
/shared/gems/activesupport-3.2.13/lib/active_support/callbacks.rb:81
                init_with at d:/installed/Develop/Java/jruby-1.7.4/lib/ruby/gems
/shared/gems/activerecord-3.2.13/lib/active_record/base.rb:523
              instantiate at d:/installed/Develop/Java/jruby-1.7.4/lib/ruby/gems
/shared/gems/activerecord-3.2.13/lib/active_record/inheritance.rb:68
              find_by_sql at d:/installed/Develop/Java/jruby-1.7.4/lib/ruby/gems
/shared/gems/activerecord-3.2.13/lib/active_record/querying.rb:38
                 collect! at org/jruby/RubyArray.java:2441
              find_by_sql at d:/installed/Develop/Java/jruby-1.7.4/lib/ruby/gems
/shared/gems/activerecord-3.2.13/lib/active_record/querying.rb:38
       logging_query_plan at d:/installed/Develop/Java/jruby-1.7.4/lib/ruby/gems
/shared/gems/activerecord-3.2.13/lib/active_record/explain.rb:41
              find_by_sql at d:/installed/Develop/Java/jruby-1.7.4/lib/ruby/gems
/shared/gems/activerecord-3.2.13/lib/active_record/querying.rb:37
             exec_queries at d:/installed/Develop/Java/jruby-1.7.4/lib/ruby/gems
/shared/gems/activerecord-3.2.13/lib/active_record/relation.rb:171
                     to_a at d:/installed/Develop/Java/jruby-1.7.4/lib/ruby/gems
/shared/gems/activerecord-3.2.13/lib/active_record/relation.rb:160
       logging_query_plan at d:/installed/Develop/Java/jruby-1.7.4/lib/ruby/gems
/shared/gems/activerecord-3.2.13/lib/active_record/explain.rb:41
                     to_a at d:/installed/Develop/Java/jruby-1.7.4/lib/ruby/gems
/shared/gems/activerecord-3.2.13/lib/active_record/relation.rb:159
                    first at d:/installed/Develop/Java/jruby-1.7.4/lib/ruby/gems
/shared/gems/activerecord-3.2.13/lib/active_record/relation/finder_methods.rb:11
7
                 __send__ at org/jruby/RubyBasicObject.java:1709
                    first at d:0
                   (root) at flow.rb:23

ActiveRecord 有没有支持分表的办法？

heliang7 — Thu, 25 Jul 2013 20:13:48 +0800

大概有这样一类表，结构都是相同的

sample_data_12222
sample_data_12223
sample_data_12224
sample_data_12225

问题是这类表有 3000 多张。先前我的想法是有多少表就用多少模型的办法

ActiveRecord::Base.connnection.tables.grep(/sample_data_\d+/).each
  Class.new(ActiveRecord::Base) do
  ...
  end
end

但是数量过多，启动后 rails 就没有反应了。

现在我的想法是用 set_table_name 来运行时改变表的指向。用 find 的时候，好像没问题，但是用 where 的时候，返回一个 Active::Relation，把它直接转变为 json 的时候

SampleData < ActiveRecord::Base

  def some
    where(...)
  end

end

some = SampleData.some #some is now Active::Relation object

render json: {data: some}  #here will generate sql below

会生成 sql 语句

select `sample_data_12223`.* from `sample_data_12222' where ...

这样的查询，当然就失败了。

当然解决办法很简单

def some
  where(...).all #now return SampleData
end

但是感觉也不太优雅。

我想请教下大家有没有比较优雅的解决这个问题的办法？

Ubuntu 12.04 更新源如何更改 dl.google.com 为 dl-ssl.google.com

heliang7 — Mon, 15 Jul 2013 17:33:02 +0800

用 rvm 安装最新的 ruby2.0 pxxx 版，提示先要更新 ubuntu。然后到下载 dl.google.com 的时候，自然就出错了。目前 dl-ssl.google.com 还是能用的，不知道怎么改成用 ssl 版的。

实在不行，考虑买云梯了，就不折腾了，唉。

如何使用 pry debug unit test

heliang7 — Mon, 04 Jun 2012 15:51:42 +0800

尝试 pry -r ./test/unit/xxx.rb

得到错误‘cannot load such file -- test_helper’

应该如何才能 debug rails 的单元测试呢？