Rails 对 View 的哈希进行迭代的问题答案

【问题标题】：Rails issue with iterating over a hash for the ViewRails 对 View 的哈希进行迭代的问题
【发布时间】：2011-12-11 23:07:46
【问题描述】：

我有这个哈希。我正在尝试在视图中渲染。我对 Rails 如此陌生，我一点也不知道该怎么做。我需要做的就是能够按 service_name 或按主机对事物进行排序，并据此构建块。我已经尝试了十几件事，但我似乎无法正常工作，所以我现在需要任何帮助。

我正在尝试做的一个例子：

下面是哈希。到目前为止，我得到的最好的只是服务名称，无需排序或其他任何内容即可独立列出。

services_hash = {
    :status => "successful",
    :service_list => [
        {
            :service_name => "oozie",
            :status => "RUNNING",
            :status_message => "Running Master Service",
            :host => "1"
        },
        {
            :service_name => "single-namenode",
            :status => "RUNNING",
            :status_message => "Running Service",
            :host => "1"
        },
        {
            :service_name => "single-database",
            :status => "RUNNING",
            :status_message => "Running Service",
            :host => "1"
        },
        {
            :service_name => "datanode",
            :status => "RUNNING",
            :status_message => "Running Service",
            :host => "1"
        },
        {
            :service_name => "secondarynamenode",
            :status => "RUNNING",
            :status_message => "Running Service",
            :host => "1"
        },
        {
            :service_name => "web",
            :status => "DEAD",
            :status_message => "Running Master Service",
            :host => "1"
        },
        {
            :service_name => "tasktracker",
            :status => "RUNNING",
            :status_message => "Running Service",
            :host => "1"
        },
        {
            :service_name => "jobtracker",
            :status => "RUNNING",
            :status_message => "Running Master Service",
            :host => "1"
        },
        {
            :service_name => "oozie",
            :status => "RUNNING",
            :status_message => "Running Master Service",
            :host => "1"
        },
        {
            :service_name => "single-namenode",
            :status => "RUNNING",
            :status_message => "Running Service",
            :host => "1"
        },
        {
            :service_name => "single-database",
            :status => "RUNNING",
            :status_message => "Running Service",
            :host => "1"
        },
        {
            :service_name => "datanode",
            :status => "RUNNING",
            :status_message => "Running Service",
            :host => "1"
        },
        {
            :service_name => "secondarynamenode",
            :status => "RUNNING",
            :status_message => "Running Service",
            :host => "1"
        },
        {
            :service_name => "web",
            :status => "DEAD",
            :status_message => "Running Master Service",
            :host => "1"
        },
        {
            :service_name => "tasktracker",
            :status => "RUNNING",
            :status_message => "Running Service",
            :host => "1"
        },
        {
            :service_name => "jobtracker",
            :status => "RUNNING",
            :status_message => "Running Master Service",
            :host => "1"
        },
        {
            :service_name => "oozie",
            :status => "RUNNING",
            :status_message => "Running Master Service",
            :host => "1"
        },
        {
            :service_name => "single-namenode",
            :status => "RUNNING",
            :status_message => "Running Service",
            :host => "1"
        },
        {
            :service_name => "single-database",
            :status => "RUNNING",
            :status_message => "Running Service",
            :host => "1"
        },
        {
            :service_name => "datanode",
            :status => "RUNNING",
            :status_message => "Running Service",
            :host => "1"
        },
        {
            :service_name => "secondarynamenode",
            :status => "RUNNING",
            :status_message => "Running Service",
            :host => "1"
        },
        {
            :service_name => "web",
            :status => "DEAD",
            :status_message => "Running Master Service",
            :host => "1"
        },
        {
            :service_name => "tasktracker",
            :status => "RUNNING",
            :status_message => "Running Service",
            :host => "1"
        },
        {
            :service_name => "jobtracker",
            :status => "RUNNING",
            :status_message => "Running Master Service",
            :host => "1"
        },
        {
            :service_name => "oozie",
            :status => "RUNNING",
            :status_message => "Running Master Service",
            :host => "1"
        },
        {
            :service_name => "single-namenode",
            :status => "RUNNING",
            :status_message => "Running Service",
            :host => "1"
        },
        {
            :service_name => "single-database",
            :status => "RUNNING",
            :status_message => "Running Service",
            :host => "1"
        },
        {
            :service_name => "datanode",
            :status => "RUNNING",
            :status_message => "Running Service",
            :host => "1"
        },
        {
            :service_name => "secondarynamenode",
            :status => "RUNNING",
            :status_message => "Running Service",
            :host => "1"
        },
        {
            :service_name => "web",
            :status => "DEAD",
            :status_message => "Running Master Service",
            :host => "1"
        },
        {
            :service_name => "tasktracker",
            :status => "RUNNING",
            :status_message => "Running Service",
            :host => "1"
        },
        {
            :service_name => "jobtracker",
            :status => "RUNNING",
            :status_message => "Running Master Service",
            :host => "1"
        },
        {
            :service_name => "oozie",
            :status => "RUNNING",
            :status_message => "Running Master Service",
            :host => "1"
        },
        {
            :service_name => "single-namenode",
            :status => "RUNNING",
            :status_message => "Running Service",
            :host => "1"
        },
        {
            :service_name => "single-database",
            :status => "RUNNING",
            :status_message => "Running Service",
            :host => "1"
        },
        {
            :service_name => "datanode",
            :status => "RUNNING",
            :status_message => "Running Service",
            :host => "1"
        },
        {
            :service_name => "secondarynamenode",
            :status => "RUNNING",
            :status_message => "Running Service",
            :host => "1"
        },
        {
            :service_name => "web",
            :status => "DEAD",
            :status_message => "Running Master Service",
            :host => "1"
        },
        {
            :service_name => "tasktracker",
            :status => "RUNNING",
            :status_message => "Running Service",
            :host => "1"
        },
        {
            :service_name => "jobtracker",
            :status => "RUNNING",
            :status_message => "Running Master Service",
            :host => "1"
        },
        {
            :service_name => "oozie",
            :status => "RUNNING",
            :status_message => "Running Master Service",
            :host => "1"
        },
        {
            :service_name => "single-namenode",
            :status => "RUNNING",
            :status_message => "Running Service",
            :host => "1"
        },
        {
            :service_name => "single-database",
            :status => "RUNNING",
            :status_message => "Running Service",
            :host => "1"
        },
        {
            :service_name => "datanode",
            :status => "RUNNING",
            :status_message => "Running Service",
            :host => "1"
        },
        {
            :service_name => "secondarynamenode",
            :status => "RUNNING",
            :status_message => "Running Service",
            :host => "1"
        },
        {
            :service_name => "web",
            :status => "DEAD",
            :status_message => "Running Master Service",
            :host => "1"
        },
        {
            :service_name => "tasktracker",
            :status => "RUNNING",
            :status_message => "Running Service",
            :host => "1"
        },
        {
            :service_name => "jobtracker",
            :status => "RUNNING",
            :status_message => "Running Master Service",
            :host => "1"
        },
        {
            :service_name => "oozie",
            :status => "RUNNING",
            :status_message => "Running Master Service",
            :host => "1"
        },
        {
            :service_name => "single-namenode",
            :status => "RUNNING",
            :status_message => "Running Service",
            :host => "1"
        },
        {
            :service_name => "single-database",
            :status => "RUNNING",
            :status_message => "Running Service",
            :host => "1"
        },
        {
            :service_name => "datanode",
            :status => "RUNNING",
            :status_message => "Running Service",
            :host => "1"
        },
        {
            :service_name => "secondarynamenode",
            :status => "RUNNING",
            :status_message => "Running Service",
            :host => "1"
        },
        {
            :service_name => "web",
            :status => "DEAD",
            :status_message => "Running Master Service",
            :host => "1"
        },
        {
            :service_name => "tasktracker",
            :status => "RUNNING",
            :status_message => "Running Service",
            :host => "1"
        },
        {
            :service_name => "jobtracker",
            :status => "RUNNING",
            :status_message => "Running Master Service",
            :host => "1"
        }
    ]
}

编辑以下是我尝试过的两件事，另一件事是其他人帮助我得出的排序结论。两者都起作用。但是当我去结合这些想法时，我惨遭失败。从那以后，我放弃了我的组合努力，希望能找到答案，以便我可以遍历哈希以重现上述图像以达到某种效果。

请注意，目前我意识到 HTML 的输出不会完全类似于图像。现在我被它的 if-else 部分困住了，因为我尝试它的方式似乎跳过了它。

<%
val = @service_hash
svcs = val[:service_list]
puts "#{svcs.size} service entries."

grouped = svcs.group_by { |svc| svc[:service_name] }
puts "#{grouped.size} named services:"

grouped.keys.sort.each do |name|
    puts "  service: #{name}"
    grouped[name].each do |svc|
        puts "     host: #{svc[:host]}"
        puts "   status: #{svc[:status]}"
        puts "           #{svc[:status_message]}"
    end
    puts '-'*40
end
%>

【问题讨论】：

我昨天提供的内容有什么问题？
那么实际的问题是什么？排序机制/等。已提供。您无法创建 HTML？
什么意思，不能提供 HTML？不知道你的意思是“宁愿让服务器端的东西像我想要的那样渲染它”。
您知道模板是在服务器上呈现的，对吧？哈希的内容不相关。既然懂 PHP，那就先用 PHP 写，再翻译成 Ruby。
所以用 PHP 编写并翻译成 Ruby。您对迭代所做的事情与 Ruby 没有太大关系，它与在适当的位置插入 HTML 标记有关。您没有描述实际的问题，您的情况非常好。

标签： ruby-on-rails hash jruby

【解决方案1】：

在 Ruby on Rails 中，puts 不会写入输出缓冲区。在 ERB 中，<%= %> 内的代码块的返回值将被写入输出。所以在你看来你的代码应该更像这样：

# ERB View Template
<%
  val = @service_hash
  svcs = val[:service_list] # This should probably be done in a controller rather than a view.
%>

<%= svcs.size %> service entries.

<%
  grouped = svcs.group_by { |svc| svc[:service_name] } # Again, this should probably be in a controller
%>

<%= grouped.size %> named services:

<% grouped.keys.sort.each do |name| %>
  service: <%= name %>
  <% grouped[name].each do |svc| %>
    host: <%= svc[:host] %>
    status: <% svc[:status] %>
    <%= svc[:status_message] %>
  <% end %>
  <%= '-'*40 %>

<% end %>

【讨论】：