Html Agility Pack returns invalid XPath
I have an HTML document opened in two windows, and I need the selected node to be synchronized betw开发者_C百科een both windows.
Using Html Agility Pack I tried:
HtmlNode myNode = GetSomeCertainNode();
string xpath = myNode.XPath; //xpath = "/#comment[1]"
// This line throws an XPathException
var reExtract = myNode.OwnerDocument.DocumentNode.SelectSingleNode(xpath);
Exception message: '/#comment[1]' has an invalid token.
I'm wondering, I took the XPath from the node itself, which means it's a proper XPath, and I use it against the same document, why does it fail, what do I miss?
Update
When selecting some other nodes I get this exception instead: Expression must evaluate to a node-set.
(xpath
contains /html[1]/body[1]/div[1]/p[3]/strong[1]/#text[1]
).
But remember that the value is taken from the node itself, therefore it's very weird. How come it's complaining that it's invalid?
The # character is illegal in an element name. A valid XPath expression that selects a comment would be /comment()[1]
According to Mak Toro's answer I created a workaround function:
private string ValidateXPath(string xpath)
{
var index = xpath.LastIndexOf("/");
var lastPath = xpath.Substring(index);
if (lastPath.Contains("#"))
{
xpath = xpath.Substring(0, index);
lastPath = lastPath.Replace("#", "");
lastPath = lastPath.Replace("[", "()[");
xpath = xpath + lastPath;
}
return xpath;
}
Now it works great.
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