使用 Perl/LibXML 获取子元素匹配条件的 XML 父元素答案

【问题标题】：Getting XML parent elements whose children match criteria using Perl/LibXML使用 Perl/LibXML 获取子元素匹配条件的 XML 父元素
【发布时间】：2013-04-25 00:07:22
【问题描述】：

我正在使用 XML::LibXML（仅限于 v1.58）。感谢Borodin 中的this 帖子我正确地获得了PROPERTY NAME="Name" 如果CLASSNAME="SharedGtTranslator" 的值。我还想要获取包含上述内容的整个 VALUE.OBJECT 父元素，并将其输出到另一个 XML 文件。

所以如果 XML 文件看起来像这样：

<CIM CIMVERSION="2.0" DTDVERSION="2.0">

  <DECLARATION>
    <DECLGROUP>
      <LOCALNAMESPACEPATH>
        <NAMESPACE NAME="ecm"/>
      </LOCALNAMESPACEPATH>

      <!-- Ecm -->

      <VALUE.OBJECT>
        <INSTANCE CLASSNAME="Ecm">
          <PROPERTY NAME="FileName" TYPE="string">
            <VALUE>/opt/sign/log/ecm.log</VALUE>
          </PROPERTY>
          <PROPERTY NAME="Log" TYPE="sint32">
            <VALUE>0</VALUE>
          </PROPERTY>
          <PROPERTY NAME="Name" TYPE="string">
            <VALUE>ECM</VALUE>
          </PROPERTY>
          <PROPERTY NAME="TimerClaim" TYPE="sint32">
            <VALUE>5000</VALUE>
          </PROPERTY>
          <PROPERTY NAME="TimerConnect" TYPE="sint32">
            <VALUE>8000</VALUE>
          </PROPERTY>
          <PROPERTY NAME="TimerNegotiate" TYPE="sint32">
            <VALUE>5000</VALUE>
          </PROPERTY>
          <PROPERTY NAME="TimerReconnect" TYPE="sint32">
            <VALUE>500</VALUE>
          </PROPERTY>
        </INSTANCE>
      </VALUE.OBJECT>

      <VALUE.OBJECT>
        <INSTANCE CLASSNAME="Ecm_Host">
          <PROPERTY.REFERENCE NAME="Parent">
            <VALUE.REFERENCE>
              <INSTANCENAME CLASSNAME="Ecm">
                <KEYBINDING NAME="Name">
                  <KEYVALUE>ECM</KEYVALUE>
                </KEYBINDING>
              </INSTANCENAME>
            </VALUE.REFERENCE>
          </PROPERTY.REFERENCE>
          <PROPERTY.REFERENCE NAME="Child">
            <VALUE.REFERENCE>
              <INSTANCENAME CLASSNAME="Host">
                <KEYBINDING NAME="Address">
                  <KEYVALUE>gtttcnss7v19</KEYVALUE>
                </KEYBINDING>
              </INSTANCENAME>
            </VALUE.REFERENCE>
          </PROPERTY.REFERENCE>
        </INSTANCE>
      </VALUE.OBJECT>

      <VALUE.OBJECT>
        <INSTANCE CLASSNAME="Ecm_ProcessClass">
          <PROPERTY.REFERENCE NAME="Parent">
            <VALUE.REFERENCE>
              <INSTANCENAME CLASSNAME="Ecm">
                <KEYBINDING NAME="Name">
                  <KEYVALUE>ECM</KEYVALUE>
                </KEYBINDING>
              </INSTANCENAME>
            </VALUE.REFERENCE>
          </PROPERTY.REFERENCE>
          <PROPERTY.REFERENCE NAME="Child">
            <VALUE.REFERENCE>
              <INSTANCENAME CLASSNAME="ProcessClass">
                <KEYBINDING NAME="ClassID">
                  <KEYVALUE>3</KEYVALUE>
                </KEYBINDING>
              </INSTANCENAME>
            </VALUE.REFERENCE>
          </PROPERTY.REFERENCE>
        </INSTANCE>
      </VALUE.OBJECT>

      <VALUE.OBJECT>
        <INSTANCE CLASSNAME="Ecm_ProcessClass">
          <PROPERTY.REFERENCE NAME="Parent">
            <VALUE.REFERENCE>
              <INSTANCENAME CLASSNAME="Ecm">
                <KEYBINDING NAME="Name">
                  <KEYVALUE>ECM</KEYVALUE>
                </KEYBINDING>
              </INSTANCENAME>
            </VALUE.REFERENCE>
          </PROPERTY.REFERENCE>
          <PROPERTY.REFERENCE NAME="Child">
            <VALUE.REFERENCE>
              <INSTANCENAME CLASSNAME="ProcessClass">
                <KEYBINDING NAME="ClassID">
                  <KEYVALUE>1</KEYVALUE>
                </KEYBINDING>
              </INSTANCENAME>
            </VALUE.REFERENCE>
          </PROPERTY.REFERENCE>
        </INSTANCE>
      </VALUE.OBJECT>

      <VALUE.OBJECT>
        <INSTANCE CLASSNAME="Ecm_ProcessClass">
          <PROPERTY.REFERENCE NAME="Parent">
            <VALUE.REFERENCE>
              <INSTANCENAME CLASSNAME="Ecm">
                <KEYBINDING NAME="Name">
                  <KEYVALUE>ECM</KEYVALUE>
                </KEYBINDING>
              </INSTANCENAME>
            </VALUE.REFERENCE>
          </PROPERTY.REFERENCE>
          <PROPERTY.REFERENCE NAME="Child">
            <VALUE.REFERENCE>
              <INSTANCENAME CLASSNAME="ProcessClass">
                <KEYBINDING NAME="ClassID">
                  <KEYVALUE>15</KEYVALUE>
                </KEYBINDING>
              </INSTANCENAME>
            </VALUE.REFERENCE>
          </PROPERTY.REFERENCE>
        </INSTANCE>
      </VALUE.OBJECT>
      <VALUE.OBJECT>
        <INSTANCE CLASSNAME="SharedGtTranslator">
          <QUALIFIER NAME="Configstate" TYPE="string">
            <VALUE>planned</VALUE>
          </QUALIFIER>
          <PROPERTY NAME="Name" TYPE="string">
            <VALUE>HLR$4,0,1,3,7240*-->HLR HLR LocalSPC: 410 SSN: 6</VALUE>
          </PROPERTY>
          <PROPERTY NAME="NatureOfAddress" TYPE="sint32">
            <VALUE>3</VALUE>
          </PROPERTY>
          <PROPERTY NAME="NetworkID" TYPE="sint32">
            <VALUE>1</VALUE>
          </PROPERTY>
          <PROPERTY NAME="NumberSeries" TYPE="sint32">
            <VALUE>7240*</VALUE>
          </PROPERTY>
          <PROPERTY NAME="NumberingPlan" TYPE="sint32">
            <VALUE>1</VALUE>
          </PROPERTY>
          <PROPERTY NAME="TranslationType" TYPE="sint32">
            <VALUE>0</VALUE>
          </PROPERTY>
        </INSTANCE>
      </VALUE.OBJECT>
      <VALUE.OBJECT>
        <INSTANCE CLASSNAME="SharedGtTranslator">
          <QUALIFIER NAME="Configstate" TYPE="string">
            <VALUE>planned</VALUE>
          </QUALIFIER>
          <PROPERTY NAME="Name" TYPE="string">
            <VALUE>HLR$4,0,1,3,7250*-->HLR HLR LocalSPC: 410 SSN: 6</VALUE>
          </PROPERTY>
          <PROPERTY NAME="NatureOfAddress" TYPE="sint32">
            <VALUE>3</VALUE>
          </PROPERTY>
          <PROPERTY NAME="NetworkID" TYPE="sint32">
            <VALUE>1</VALUE>
          </PROPERTY>
          <PROPERTY NAME="NumberSeries" TYPE="sint32">
            <VALUE>7250*</VALUE>
          </PROPERTY>
          <PROPERTY NAME="NumberingPlan" TYPE="sint32">
            <VALUE>1</VALUE>
          </PROPERTY>
          <PROPERTY NAME="TranslationType" TYPE="sint32">
            <VALUE>0</VALUE>
          </PROPERTY>
        </INSTANCE>
      </VALUE.OBJECT>
    </DECLGROUP>

  </DECLARATION>
</CIM>

新文件将只包含以下内容：

<CIM>
  <DECLARATION>
    <DECLGROUP>
          <VALUE.OBJECT>
            <INSTANCE CLASSNAME="SharedGtTranslator">
              <QUALIFIER NAME="Configstate" TYPE="string">
                <VALUE>planned</VALUE>
              </QUALIFIER>
              <PROPERTY NAME="Name" TYPE="string">
                <VALUE>HLR$4,0,1,3,7240*-->HLR HLR LocalSPC: 410 SSN: 6</VALUE>
              </PROPERTY>
              <PROPERTY NAME="NatureOfAddress" TYPE="sint32">
                <VALUE>3</VALUE>
              </PROPERTY>
              <PROPERTY NAME="NetworkID" TYPE="sint32">
                <VALUE>1</VALUE>
              </PROPERTY>
              <PROPERTY NAME="NumberSeries" TYPE="sint32">
                <VALUE>7240*</VALUE>
              </PROPERTY>
              <PROPERTY NAME="NumberingPlan" TYPE="sint32">
                <VALUE>1</VALUE>
              </PROPERTY>
              <PROPERTY NAME="TranslationType" TYPE="sint32">
                <VALUE>0</VALUE>
              </PROPERTY>
            </INSTANCE>
          </VALUE.OBJECT>
          <VALUE.OBJECT>
            <INSTANCE CLASSNAME="SharedGtTranslator">
              <QUALIFIER NAME="Configstate" TYPE="string">
                <VALUE>planned</VALUE>
              </QUALIFIER>
              <PROPERTY NAME="Name" TYPE="string">
                <VALUE>HLR$4,0,1,3,7250*-->HLR HLR LocalSPC: 410 SSN: 6</VALUE>
              </PROPERTY>
              <PROPERTY NAME="NatureOfAddress" TYPE="sint32">
                <VALUE>3</VALUE>
              </PROPERTY>
              <PROPERTY NAME="NetworkID" TYPE="sint32">
                <VALUE>1</VALUE>
              </PROPERTY>
              <PROPERTY NAME="NumberSeries" TYPE="sint32">
                <VALUE>7250*</VALUE>
              </PROPERTY>
              <PROPERTY NAME="NumberingPlan" TYPE="sint32">
                <VALUE>1</VALUE>
              </PROPERTY>
              <PROPERTY NAME="TranslationType" TYPE="sint32">
                <VALUE>0</VALUE>
              </PROPERTY>
            </INSTANCE>
          </VALUE.OBJECT>
    </DECLGROUP>

  </DECLARATION>
</CIM>

【问题讨论】：

看来我找到了答案here

标签： xml perl xml-libxml

【解决方案1】：

如果您需要VALUE.OBJECT 结构，那么我建议您先找到这些结构，然后在其中查找为您提供名称的PROPERTY 元素。

这段代码符合这个想法。它在数据中查找所有VALUE.OBJECT 元素，其INSTANCE 子元素的CLASSNAME 属性等于SharedGtTranslator。对于这些元素，整个元素的 XML 使用toString 显示，通过查找INSTANCE 子元素，然后查找具有等于NAME 属性的PROPERTY 子元素，找到并显示名称Name.

我还更改了从文件中解析数据的方式，正如您所说的，您遇到了没有 load_xml 方法的 XML::LibXML 版本。

请注意，findnodes 方法将始终返回节点列表，如果调用在列表上下文中，则作为 Perl 列表，如果在 scdalar 上下文中，则作为 XML::LibXML::NodeList 对象。无论 XPath 表达式有多个匹配、一个匹配还是零匹配都是如此，如果您有任何疑问，您应该在继续处理之前检查找到的节点数。

use strict;
use warnings;

use XML::LibXML;

my $doc = XML::LibXML->new(no_blanks => 1)->parse_file($file1);

my @value_objects = $doc->findnodes('//VALUE.OBJECT[INSTANCE[@CLASSNAME = "SharedGtTranslator"]]');

for my $value_object (@value_objects) {

  print "\n";
  print $value_object->toString(1), "\n";
  print "\n";

  my @names = $value_object->findnodes('INSTANCE/PROPERTY[@NAME = "Name"]');
  print $names[0]->textContent, "\n";
}

【讨论】：