villins (villins)

请教个 Sinatra ActiveRecord 时间时区问题

villins — Tue, 14 Jun 2016 17:45:44 +0800

在 sinatra 设置了 Time 的时区如下：

Time.zone = "Beijing"
ActiveRecord::Base.default_timezone = :local

然后获取 model 里面的时间字段

Show.last.show_time
2016-06-14 15:20:00 +0800

Show.last.show_time.utc
2016-06-14 07:20:00 UTC

这里用 active_record 获取展示的时间值是错误的设置了北京时区，获取值不加 8 小时却设置成 CST，取 utc 值却在已是 utc 时间再减 8 小时

从 rails 获取出来的正确值如下

Show.last.show_time
Tue, 14 Jun 2016 23:20:00 CST +08:00

Show.last.show_time.utc

2016-06-14 15:20:00 UTC

创建时间居然也没有转换成 utc 时间入库，wtf 一样是 ActiveRecord::Base 的子类在 sinatra 的 datetime 字段的 class 居然是 Time，而在 rails 的是 ActiveSupport::TimeWithZone < Object

java 加密获取裸公钥转换成 ruby code

villins — Tue, 12 Jan 2016 17:37:21 +0800

谷歌许久，查文档，想破头皮，依旧无解，求有没有什么建议的方式实现这下面代码的转换？

public class RsaKeyGenerateDemo{
  KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance("RSA");
  keyPairGen.initialize(new RSAKeyGenParameterSpec(1408, new BigInteger("3")), new SecureRandom());
  KeyPair keyPair = keyPairGen.generateKeyPair();
  PublicKey publicKey=keyp.getPublic();
  System.out.println(publicKey.getModulus().toString(16).toUpperCase();)
}

更新：貌似这个 rsa gem 有点相似

Object#try 对潜在的 Rails 中的 nil 调用方法

villins — Sat, 08 Aug 2015 12:23:46 +0800

对潜在的 Rails 中的 nil 调用方法

在 Rails 中，我们平常可以使用很多非常便利的方法，其中有一个我认为有点 cool 的方法 —— Object#try 它有什么作用昵，它可以让我们调用一个对象不用担心这个对象是否为 nil，因此抛出异常。如何使用它，如下

"HELLO WORLD".try(:downcase)
=> "hello world"

看起来跟 Object#send 差不多，都是传递 symbol，args 和 block，但是差别就是上面所说，nil 使用 send 去调用不属于 nil 的方法，还是会引起异常。

nil.send(:downcase)
NoMethodError: undefined method `downcase' for nil:NilClass
nil.try(:downcase)
=> nil

拿我们项目中的代码来举例

before 没有使用 try

# helper method
def ymdhm_strftime(time)
  time.strftime("%Y-%m-%d %H:%M") if time.present?
end
# erb 
<p>上映 : &nbsp; <%= ymd_strftime(@film.show_date) %></p>

after 使用 try

# 可以直接在页面使用
<p>上映 : &nbsp; <%= @film.show_date.try(strftime, "%Y-%m-%d %H:%M") %></p>
＃ 可以重构 helper method
def ymdhm_strftime(time)
  time.try(strftime, "%Y-%m-%d %H:%M")
end

还有 try 可以链式调用

"HELLO WORLD".try(:downcase).try(:capitalize)
=> "Hello world"

它虽然能给我们带来便利，但是我们不能因此滥用它

# object_try.rb
require 'benchmark/ips'
require 'active_support/core_ext/object/try'
Benchmark.ips do |x|
  x.report("try method") { "hello".try(:upcase) }
  x.report("call method") { "hello".upcase }
  x.compare!
end

ruby object_try.rb
Calculating -------------------------------------
          try method    62.882k i/100ms
         call method    74.916k i/100ms
-------------------------------------------------
          try method      1.861M (± 8.7%) i/s -      9.244M
         call method      2.737M (± 8.2%) i/s -     13.635M
Comparison:
         call method:  2736550.4 i/s
          try method:  1861489.0 i/s - 1.47x slower

rails tutorial 中 ajax 问题

villins — Sun, 28 Oct 2012 21:15:10 +0800

在按照书中代码编写 follow 和 unfollow 按钮时，添加上 ajax 功能后

点击之后就会出现错误

下面为点 unfollow 点击出现的错误信息

Started DELETE "/relationships/1" for 127.0.0.1 at 2012-10-28 20:53:33 +0800
Processing by RelationshipsController#destroy as JS
  Parameters: {"utf8"=>"✓", "authenticity_token"=>"A5HEZNjXLdmCzAO5BXmPXb3X2VkHs8rDpqrw/zErq0k=", "commit"=>"Unfollow", "id"=>"1"}
  User Load (0.2ms)  SELECT "users".* FROM "users" WHERE "users"."id" = 1 LIMIT 1
  Rendered users/_unfollow.html.erb (2.2ms)
  Rendered relationships/destroy.js.erb (2.9ms)
Completed 500 Internal Server Error in 6ms

ActionView::Template::Error (Called id for nil, which would mistakenly be 4 -- if you really wanted the id of nil, use object_id):
    1: <%= form_for(current_user.relationships.find_by_followed_id(@user.id),
    2:              :html => { :method => :delete },
    3:              :remote => true) do |f| %>
    4:   <div class="actions"><%= f.submit "Unfollow" %></div>
  app/views/users/_unfollow.html.erb:1:in `_app_views_users__unfollow_html_erb__1917503669697459990_70063164482580'
  app/views/relationships/destroy.js.erb:1:in `_app_views_relationships_destroy_js_erb___120623583448683911_70063171541040'

_destroy.js.erb

$("follow_form").update("<%= escape_javascript(render('users/unfollow')) %>")
$("followers").update('<%= "#{@user.followers.count} followers" %>')

查找了好久，找不出解决方法

还有求点 rails 中用 ajax 的资料

rails tutorial 里面的问题

villins — Sun, 14 Oct 2012 13:10:36 +0800

如下面这个代码

before_save :encrypt_password

def has_password?(submitted_password)
  encrypted_password == encrypt(submitted_password)
end
private
  def encrypt_password
    self.salt = make_salt if new_record?
  self.encrypted_password = encrypt(password)
  end
  def encrypt(string)
    secure_hash("#{salt}--#{string}")
  end
  def make_salt
    secure_hash("#{Time.now.utc}--#{password}")
  end
  def secure_hash(string)
    Digest::SHA2.hexdigest(string)
  end
end

中的

def has_password?(submitted_password)
  encrypted_password == encrypt(submitted_password)
end

的 encrypted_password 是使用的 encrypted_password 方法还是 model 的变量的呢？

rails tutorails 中的这段代码

$ rails console --sandbox
>> User.create(:name => "Michael Hartl", :email => "mhartl@example.com",
:password => "foobar", :password_confirmation => "foobar")
>> user = User.find_by_email("mhartl@example.com")
>> user.has_password?("foobar")

返回是 true 而我测试的是 false 检查出来的原因，在调用 has_password？中的 self.encrypted_password = encrypt(password) 的 password 是空值

是不是 rails tutorails 书上错误，还是我理解代码写错了，忘指点迷津下

/config/environment.rb:6:in `': undefined local variable or method `config' for main:Object (NameError)

villins — Sat, 26 May 2012 10:53:11 +0800

我在 environment.rb 中添加了一句 config.gem 'tiny_mce'，具体如下：

Load the rails application

require File.expand_path('../application', FILE)

Initialize the rails application

MyBlog::Application.initialize! config.gem 'tiny_mce'

一启动服务就出现如下错误：

/home/villins/MyBlog/config/environment.rb:6:in <top (required)>': undefined local variable or methodconfig' for main:Object (NameError) from /home/villins/MyBlog/config.ru:4:in require' from /home/villins/MyBlog/config.ru:4:inblock in

' from /home/villins/.rvm/gems/ruby-1.9.3-p194/gems/rack-1.4.1/lib/rack/builder.rb:51:in

instance_eval'
    from /home/villins/.rvm/gems/ruby-1.9.3-p194/gems/rack-1.4.1/lib/rack/builder.rb:51:in

initialize' from /home/villins/MyBlog/config.ru:1:in

new'
    from /home/villins/MyBlog/config.ru:1:in

' from /home/villins/.rvm/gems/ruby-1.9.3-p194/gems/rack-1.4.1/lib/rack/builder.rb:40:in

eval'
    from /home/villins/.rvm/gems/ruby-1.9.3-p194/gems/rack-1.4.1/lib/rack/builder.rb:40:in

parse_file' from /home/villins/.rvm/gems/ruby-1.9.3-p194/gems/rack-1.4.1/lib/rack/server.rb:200:in

app'
    from /home/villins/.rvm/gems/ruby-1.9.3-p194/gems/railties-3.2.3/lib/rails/commands/server.rb:46:in

app' from /home/villins/.rvm/gems/ruby-1.9.3-p194/gems/rack-1.4.1/lib/rack/server.rb:301:in

wrapped_app'
    from /home/villins/.rvm/gems/ruby-1.9.3-p194/gems/rack-1.4.1/lib/rack/server.rb:252:in

start' from /home/villins/.rvm/gems/ruby-1.9.3-p194/gems/railties-3.2.3/lib/rails/commands/server.rb:70:in

start'
    from /home/villins/.rvm/gems/ruby-1.9.3-p194/gems/railties-3.2.3/lib/rails/commands.rb:55:in

block in ' from /home/villins/.rvm/gems/ruby-1.9.3-p194/gems/railties-3.2.3/lib/rails/commands.rb:50:in

tap'
    from /home/villins/.rvm/gems/ruby-1.9.3-p194/gems/railties-3.2.3/lib/rails/commands.rb:50:in

' from script/rails:6:in

require'
    from script/rails:6:in

请问有什么解决方法吗？