views:

936

answers:

2

I am attempting to use the HtmlAgilityPack library to parse some links in a page, but I am not seeing the results I would expect from the methods. In the following I have a HtmlNodeCollection of links. For each link I want to check if there is an image node and then parse its attribures but the SelectNodes and SelectSingleNode methods of linkNode seems to be searching the parent document not the childNodes of linkNode what gives?

HtmlDocument htmldoc = new HtmlDocument();
htmldoc.LoadHtml(content);
HtmlNodeCollection linkNodes = htmldoc.DocumentNode.SelectNodes("//a[@href]");

foreach(HtmlNode linkNode in linkNodes)
{
    string linkTitle = linkNode.GetAttributeValue("title", string.Empty);
    if (linkTitle == string.Empty)
    {
        HtmlNode imageNode = linkNode.SelectSingleNode("/img[@alt]");     
    }
}

Is there any other way I could get the alt attribute of the image childnode of linkNode if it exists?

+2  A: 

You should remove the forwardslash prefix from "/img[@alt]" as it signifies that you want to start at the root of the document.

HtmlNode imageNode = linkNode.SelectSingleNode("img[@alt]");
Richard Szalay
Errrm OK. That was pretty daft of me. I thought I was missing something. Sorry for wasting question space Thanks.
Sheff
There's always plenty of space :)
Richard Szalay
+2  A: 

Also, Watch out for Null Check. SelectNodes returns null instead of blank collection.

HtmlNodeCollection linkNodes = htmldoc.DocumentNode.SelectNodes("//a[@href]");

**if(linkNodes!=null)**
{
   foreach(HtmlNode linkNode in linkNodes)
  {
     string linkTitle = linkNode.GetAttributeValue("title", string.Empty);
     if (linkTitle == string.Empty)
     {
       **HtmlNode imageNode = linkNode.SelectSingleNode("img[@alt]");**   
     }
  }
}
msqr
Which was a really stupid design decision IMO. There's no reason it *shouldn't* return an empty collection.
Mark