将新节点添加到一组现有节点 (Perl XML::LibXML)

Question

使用 Perl XML::LibXML 库，我尝试使用循环向 XML 文档中的一组现有节点中的每个节点添加一个新节点。这是我迄今为止的尝试：

#!/usr/bin/perl -w
use 5.14.2;
use XML::LibXML;

my $filename = "xml_doc.xml";
my $parser = XML::LibXML->new();
$parser->keep_blanks(0);
my $dom = $parser->parse_file($filename);

for my $node ($dom->findnodes("/poem/stanza/v"))
{
    my $elm = $dom->createElement('newnode');
    $elm->appendText('This is a new node');
    $_->addChild($elm);
}

say $dom->toString(1);

文件'xml_doc.xml'：

<?xml version="1.0" encoding="UTF-8"?>
<poem>
<stanza>
<v>As I was going to Bonner,</v>
<v>Upon my word of honor,</v>
<v>I met a pig</v>
<v>Without a wig,</v>
<v>As I was going to Bonner.</v>
</stanza>
</poem>

程序失败，并出现错误“无法在 batch_add_nodes.pl 第 16 行的未定义值上调用方法“addChild”。”

欢迎任何提示。

Answer 1

您需要决定您的 for 循环迭代器变量是 $node 还是 $_ :-)

如果我将 $_->addChild($elm) 替换为 $node->addChild($elm) 您的代码可以正常工作并给出以下输出：

<?xml version="1.0" encoding="UTF-8"?>
<poem>
  <stanza>
    <v>As I was going to Bonner,<newnode>This is a new node</newnode></v>
    <v>Upon my word of honor,<newnode>This is a new node</newnode></v>
    <v>I met a pig<newnode>This is a new node</newnode></v>
    <v>Without a wig,<newnode>This is a new node</newnode></v>
    <v>As I was going to Bonner.<newnode>This is a new node</newnode></v>
  </stanza>
</poem>