ruby-on-rails - 使用 ruby​​ 格式化数据数组

Question

我正在尝试使用 ruby​​ 从 PostgreSQL 获取数据并将它们存储到一个数组中，为此我有一个小脚本:

脚本:

require 'pg'  

conn=PGconn.connect( :hostaddr=>"192.168.111.136", :port=>5432, :dbname=>"sentinel_poc",:user=>"sdn_mehdi", :password=>'skyline123')  

res = conn.exec("SELECT dns_name FROM dns_table group by dns_name").to_a  

a_dns = []  

res.each { |r| a_dns << r }  
puts a_dns.join(",")  

结果是:

{"dns_name"=>"youtube.com                                       "},{"dns_name"=>"stackoverflow.com                                         "},{"dns_name"=>"cisco.com                                         "},{"dns_name"=>"facebook.com                                      "},{"dns_name"=>"yahoo.com                                         "},{"dns_name"=>"onf.com                                           "},{"dns_name"=>"safe.com                                          "},{"dns_name"=>"linkedin.com                                      "},{"dns_name"=>"amazon.com                                        "},{"dns_name"=>"google.com                                        "},{"dns_name"=>"java.com                                          "},{"dns_name"=>"live.com                                          "},{"dns_name"=>"rails.com                                         "},{"dns_name"=>"postgresql.com                                    "},{"dns_name"=>"hp.com                                            "},{"dns_name"=>"wikipedia.org                                     "}

我需要的只是每个域名的名称!类似于 {"youtube.com","google.com","java.com","rails.com","hp.com"}

如有任何建议，我们将不胜感激。

Answer 1

我认为你需要:

res.flat_map(&:values)
# or if you have hashes having size more then 1, then use the below
res.map { |h| h["dns_name"] }
# to strip leading and trailing whit spaces
res.map { |h| h["dns_name"].strip }