mysql2与ruby问题

试图获得安装在Ubuntu上的gem mysql2，我尝试了所有的建议，但我不能让它运行。这是我的应用程序中的错误。mysql2与ruby问题

./bla.rb:65:in `post_init': undefined method `query' for nil:NilClass (NoMethodError) 
    from /var/lib/gems/1.8/gems/eventmachine-0.12.10/lib/em/timers.rb:51:in `call' 
    from /var/lib/gems/1.8/gems/eventmachine-0.12.10/lib/em/timers.rb:51:in `fire' 
    from /var/lib/gems/1.8/gems/eventmachine-0.12.10/lib/eventmachine.rb:256:in `call' 
    from /var/lib/gems/1.8/gems/eventmachine-0.12.10/lib/eventmachine.rb:256:in `run_machine' 
    from /var/lib/gems/1.8/gems/eventmachine-0.12.10/lib/eventmachine.rb:256:in `run' 
    from ./bla.rb:234:in `start_server' 
    from ./bin/minibardaemon:15 
    from /var/lib/gems/1.8/gems/daemons-1.1.8/lib/daemons/application.rb:254:in `call' 
    from /var/lib/gems/1.8/gems/daemons-1.1.8/lib/daemons/application.rb:254:in `start_proc' 
    from /var/lib/gems/1.8/gems/daemons-1.1.8/lib/daemons/application.rb:263:in `call' 
    from /var/lib/gems/1.8/gems/daemons-1.1.8/lib/daemons/application.rb:263:in `start_proc' 
    from /var/lib/gems/1.8/gems/daemons-1.1.8/lib/daemons/application.rb:295:in `start' 
    from /var/lib/gems/1.8/gems/daemons-1.1.8/lib/daemons/controller.rb:73:in `run' 
    from /var/lib/gems/1.8/gems/daemons-1.1.8/lib/daemons.rb:197:in `run_proc' 
    from /var/lib/gems/1.8/gems/daemons-1.1.8/lib/daemons/cmdline.rb:109:in `call' 
    from /var/lib/gems/1.8/gems/daemons-1.1.8/lib/daemons/cmdline.rb:109:in `catch_exceptions' 
    from /var/lib/gems/1.8/gems/daemons-1.1.8/lib/daemons.rb:196:in `run_proc'

我已经安装了所有的包被推荐并通过安装宝石，但仍然没有运气mysql2。

libmysqlclient-dev

已安装。

Im在Ubuntu上。

# gem -v 
1.3.7 

# ruby -v 
ruby 1.8.7 (2010-08-16 patchlevel 302) [x86_64-linux]

安装宝石

# gem install mysql 
Building native extensions. This could take a while... 
Successfully installed mysql-2.8.1 
1 gem installed 
Installing ri documentation for mysql-2.8.1... 
Installing RDoc documentation for mysql-2.8.1... 



# gem install mysql2 
Building native extensions. This could take a while... 
Successfully installed mysql2-0.3.11 
1 gem installed 
Installing ri documentation for mysql2-0.3.11... 
Installing RDoc documentation for mysql2-0.3.11... 


    def create_mysql2 
    begin 
     mysql2 = Mysql2::EM::Client.new(
     :username => DBUSER, 
     :password => DBPASS, 
     :host  => DBHOST, 
     :port  => DBPORT, 
     :socket => DBSOCKET, 
     :database => DBNAME 
    ) 
     return mysql2 
    rescue Mysql2::Error => exception 
     $stderr.puts "Mysql Error: #{ exception.message }" 
     EventMachine::stop_event_loop 
    end 
    end

...

begin 
    mysql2 = create_mysql2 
rescue Exception => ex 
    p ex 
end 

    # query the db every x seconds. 
    EventMachine::add_periodic_timer(QUERY_INTERVAL) do 
     defer1 = mysql2.query "SELECT * FROM table LIMIT #{QUERY_LIMIT}"

来源

2012-03-02 Kieran Andrews

并不真的像mysql2宝石的问题，请你告诉你bla.rb文件65'th行？可能还有一些围绕它的线条。

它实际上看起来像你的mysql2客户端由于某种原因得到未初始化。我会建议检查是否是这样工作的：

require 'mysql2' 
mysql_client = Mysql2::Client.new(:host => "localhost", :username => "root") 
mysql_client.query('sql .. ')

如果是这样，显然有一个问题，在您的脚本

来源

2012-03-02 12:09:49

线65：defer1 = mysql2.query“SELECT * FROM minibar_usage其中状态=假LIMIT ＃{QUERY_LIMIT}“ - >用更多的代码更新了我的问题。 – 2012-03-02 12:22:34

谢谢，你指出我在正确的方向 - 这是一个严峻的问题：https：//github.com/brianmario/mysql2/issues/112 - 每次都需要启动连接。 – 2012-03-02 12:43:11

mysql2与ruby问题

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