Question

I’m using the HTML agility pack to scrape a website. I’m looking though all the div tags that contain “a” elements for certain text. Here is the sample code:

 var showLocations = (from div in document.DocumentNode.Descendants("div")
                                 from a in div.DescendantNodes().Where(x => x.Name == "a")
                                 where a.Attributes["href"].Value.Contains("show_locs=Y")
                                 select a).SingleOrDefault();

However, instead of returning null if the element cannot be found, it throws a “Null Reference Exception”. Why is that?

Answer 1

My guess is that there are <a> tags without href attributes (i.e anchors instead of links). try a.GetAttributeValue("href", "").Contains... instead.