将新节点添加到一组现有节点（Perl XML :: LibXML）

Question

使用Perl XML :: LibXML库，我正在尝试使用循环向XML文档中的每个现有节点添加一个新节点。这是我到目前为止的尝试：

#!/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，错误“无法调用方法”addChild“在batch_add_nodes.pl第16行的未定义值上。”

任何提示都会受到欢迎。

Answer 1

你需要决定你的for循环迭代器变量是$node还是$_ :-)

如果我用$_->addChild($elm)替换$node->addChild($elm)你的代码可以工作并提供这个输出：

<?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>