Question
Using an xpath expression in the HTML Agility Pack, I'm attempting to get the value of the second property of a meta tag: Using a meta tag,
<meta name="pubdate" content="2012-08-30" />
I'm using this xml path expression:
//meta[@name='pubdate']/@content
But it gives back nothing. I looked about and attempted to put this remedy into practice:
//meta[@name='pubdate']/string(@content)
Another approach is:
string(//meta[@name='pubdate']/@content)
But the HTML Agility Pack throws an XML error. A other approach did not perform as well.
//meta[@name='pubdate']/data(@content)
For various reasons, I only wanted to utilize xml paths (and not html agility pack functions to get the attribute value). I utilize the function listed below:
date = TextfromOneNode(document.DocumentNode.SelectSingleNode(".//body"), "meta[@name='pubdate']/@content");
public static string TextfromOneNode(HtmlNode node, string xmlPath)
{
string toReturn = "";
if(node.SelectSingleNode(xmlPath) != null)
{
toReturn = node.SelectSingleNode(xmlPath).InnerText;
}
return toReturn;
}
So far, it seems that there is no straightforward method to get an attribute value using an xml path expression. Any thoughts?
Accepted Answer
A technique usingHtmlNodeNavigator
:
public static string TextfromOneNode(HtmlNode node, string xmlPath)
{
string toReturn = "";
var navigator = (HtmlAgilityPack.HtmlNodeNavigator)node.CreateNavigator();
var result = navigator.SelectSingleNode(xmlPath);
if(result != null)
{
toReturn = result.Value;
}
return toReturn;
}
The sample console program shown below showsHtmlNodeNavigator.SelectSingleNode()
Uses XPath that return attribute as well as XPath that return element:
var raw = @"<div>
<meta name='pubdate' content='2012-08-30' />
<span>foo</span>
</div>";
var doc = new HtmlAgilityPack.HtmlDocument();
doc.LoadHtml(raw);
var navigator = (HtmlAgilityPack.HtmlNodeNavigator)doc.CreateNavigator();
var xpath1 = "//meta[@name='pubdate']/@content";
var xpath2 = "//span";
var result = navigator.SelectSingleNode(xpath1);
Console.WriteLine(result.Value);
result = navigator.SelectSingleNode(xpath2);
Console.WriteLine(result.Value);
output:
2012-08-30
foo
Popular Answer
XML Linq use
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Xml;
using System.Xml.Linq;
namespace ConsoleApplication1
{
class Program
{
static void Main(string[] args)
{
string input = "<meta name=\"pubdate\" content=\"2012-08-30\" />";
XElement meta = XElement.Parse(input);
DateTime output = (DateTime)meta.Attribute("content");
}
}
}
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