未定义的方法' execute_query'为零:NilClass

时间:2013-09-16 21:45:12

标签: ruby-on-rails ruby jruby jrubyonrails

我想连接到db并使用JRuby执行一个非常简单的查询。它正在建立连接但未能执行查询。以下是代码:

  require 'oracle_connection'

 #Edit these for your database schema

class OracleConnectionDriver

   def initialize(user, pwd, url)
      print "Run at #{Time.now} using JRuby #{RUBY_VERSION}\n\n"user
      @conn = OracleConnection.new(user, pwd, url)
      puts #@conn, "\n"
   end

  def is_user?(user_name)
    puts "Checking if user exists: "
      select_sql = <<-EOF
        SELECT COUNT(*)
        FROM users
        WHERE username = upper('#{user_name})
        EOF

    select_stmt = #@conn.create_statement
    reselt_set = select_stmt.execute_query(select_sql)
     while(result_set.next)
        puts " Resultset [#{result_set.getInt(1)}]"
     end
   end


  print "\nEnded at #{Time.now}\n"

end

test_connection =  OracleConnectionDriver.new('USERNAME', 'PWD', 'jdbc:oracle:thin:@XXXXX:8888/YYYY')
test_connection.is_user?('ABC')

运行此功能时失败并显示以下错误消息:

ruby test_connection.rb

Ended at 2013-09-16 14:28:31 -0700
Run at 2013-09-16 14:28:31 -0700 using JRuby 1.9.2


Checking if user exists:
NoMethodError: undefined method `execute_query' for nil:NilClass
is_user_p_ at test_connection.rb:27
  (root) at test_connection.rb:40

任何人都可以帮我解决这个问题吗?谢谢!

2 个答案:

答案 0 :(得分:1)

看起来你在这一行有问题:

select_stmt = #@conn.create_statement

#字符已注释掉该分配,因此您的select_stmt变量未初始化。

答案 1 :(得分:0)

select_stmt = #@conn.create_statement

这是对右边的评论。所以在下一行:

reselt_set = select_stmt.execute_query(select_sql)

select_stmt为nil ...因此出现错误消息。