Html – Getting meta tag attribute with HTML Agility Pack using XPATH

htmlhtml-agility-packxpath

META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=iso-8859-1" />
TITLE>Microsoft Corporation
META http-equiv="PICS-Label" content="(PICS-1.1 "http://www.rsac.org/ratingsv01.html" l gen true r (n 0 s 0 v 0 l 0))" />
META NAME="KEYWORDS" CONTENT="products; headlines; downloads; news; Web site; what's new; solutions; services; software; contests; corporate news;" />
META NAME="DESCRIPTION" CONTENT="The entry page to Microsoft's Web site. Find software, solutions, answers, support, and Microsoft news." />
META NAME="MS.LOCALE" CONTENT="EN-US" />
META NAME="CATEGORY" CONTENT="home page" />

I'd like to know what XPATH I would need to get the value of the Content attribute of the Category meta tag using HTML Agility Pack. (I removed the first < of each line in the html code so it would post).

Best Answer

For a long time HtmlAgilityPack didn't have the ability to directly query an attribute value. You had to loop over the list of meta nodes. Here's one way:

var doc = new HtmlDocument();
doc.LoadHtml(htmlString);

var list = doc.DocumentNode.SelectNodes("//meta"); 
foreach (var node in list)
{
    string content = node.GetAttributeValue("content", "");
}

But it looks like there is an experimental xpath release that will let you do that.

doc.Document.SelectNodes("//meta/@content")

will return a list of HtmlAttribute objects.

Related Solutions

C# – How to use HTML Agility pack

First, install the HTMLAgilityPack nuget package into your project.

Then, as an example:

HtmlAgilityPack.HtmlDocument htmlDoc = new HtmlAgilityPack.HtmlDocument();

// There are various options, set as needed
htmlDoc.OptionFixNestedTags=true;

// filePath is a path to a file containing the html
htmlDoc.Load(filePath);

// Use:  htmlDoc.LoadHtml(xmlString);  to load from a string (was htmlDoc.LoadXML(xmlString)

// ParseErrors is an ArrayList containing any errors from the Load statement
if (htmlDoc.ParseErrors != null && htmlDoc.ParseErrors.Count() > 0)
{
    // Handle any parse errors as required

}
else
{

    if (htmlDoc.DocumentNode != null)
    {
        HtmlAgilityPack.HtmlNode bodyNode = htmlDoc.DocumentNode.SelectSingleNode("//body");

        if (bodyNode != null)
        {
            // Do something with bodyNode
        }
    }
}

(NB: This code is an example only and not necessarily the best/only approach. Do not use it blindly in your own application.)

The HtmlDocument.Load() method also accepts a stream which is very useful in integrating with other stream oriented classes in the .NET framework. While HtmlEntity.DeEntitize() is another useful method for processing html entities correctly. (thanks Matthew)

HtmlDocument and HtmlNode are the classes you'll use most. Similar to an XML parser, it provides the selectSingleNode and selectNodes methods that accept XPath expressions.

Pay attention to the HtmlDocument.Option?????? boolean properties. These control how the Load and LoadXML methods will process your HTML/XHTML.

There is also a compiled help file called HtmlAgilityPack.chm that has a complete reference for each of the objects. This is normally in the base folder of the solution.

Html – set charset in rails application

Have your Rails application set the Content-type header, and then you won't need to worry about what Apache is doing.

response.headers['Content-type'] = 'text/html; charset=utf-8'

You may also want to add

<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />

to the page itself, so that if someone saves it to disk, it will load with the correct charset.

Best Answer

Related Solutions

C# – How to use HTML Agility pack

Html – set charset in rails application

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