Apex regex to get html child tag and its content? [closed]

Question

I have below HTML tag and i need to extract TAG child tag and its element.

<h3 class="large lheight20 margintop10">
<a href="https://google.com" class="marginright5 link linkWithHash detailsLink">
<span>get the content</span>
</a>

</h3>

I want to extract following string from the code.

 <a href="https://google.com" class="marginright5 link linkWithHash detailsLink">
    <span>get the content</span>
    </a>

I have tried the following but it does not work.

<h3[^<>]*class="large lheight20 margintop10"[^<>]*>(?<content>.*?)</h3>

Answer 1

I was able to use the following pattern:

(?si)<h3[^>]+?>(.*)<\/h3>

Explanation:

• (?si)
  • The s flag indicates that . should match newline characters.
  • Might as well use the i flag to make it case insensitive.
• <h3[^>]+?>
  • Match the opening tag.
• (.*)
  • Match all characters as match group 1.
• <\/h3>
  • Match the closing tag.

---

Here is the script I used in Execute Anonymous:

String markup = '<h3 class="large lheight20 margintop10">\n' +
    '<a href="https://google.com" class="marginright5 link linkWithHash detailsLink">\n' +
    '<span>get the content</span>\n' +
    '</a>\n\n</h3>';
Matcher regex = Pattern.compile('(?si)<h3[^>]+?>(.*)<\\/h3>').matcher(markup);
system.debug(regex.find());
system.debug(regex.group(1));

Answer 2

Regular expressions work on regular languages, but HTML is not a regular language. So, while you can do some limited extraction of html using a regexp, regexps are not the right tool for the job.

Instead, I'd suggest using the Dom.Document class and the Dom.XmlNode class

A brief example to get you going

Dom.Document inDoc = new Dom.Document();
inDoc.load(htmlStringInput);

Dom.XmlNode root = inDoc.getRootElement();

Dom.XmlNode aTag = root.getChildElement('a', null);
Dom.XmlNode spanTag = aTag.getChildElement('span', null);

System.debug('extracted hyperlink: ' + aTag.getAttributeValue('href', null));
System.debug('extracted link text: ' + spanTag.getText());

I'm not exactly sure how you'd go about getting the string representation of the link tag (from the Dom.XmlNode) once you extracted it from the root, and I don't have the ability to play around with it today. I'll try to keep this in mind and see if I can work something out tomorrow if you truly need the entire content (attributes and children) of the link tag instead of the href and span text.