Question

i have the follow code:

searchResults.SearchResultCollection.Add(
                new SearchResult()
                    {
                        Header =
                        HttpUtility.HtmlDecode(
                        htmlDocument.DocumentNode
                        .SelectSingleNode(initialXPath + "h3") 
                        .InnerText),
                        Link = HttpUtility.HtmlDecode(
                        htmlDocument.DocumentNode
                        .SelectSingleNode(initialXPath + "div/cite")
                        .InnerText)
                    }
                );

Sometimes htmlDocument.DocumentNode.SelectSingleNode(….) returns null and my application crashed with NullReferenceException. Ofcourse i can write code which check returned value on null reference but then code will be overly verbose. What is graceful way to do that?

Answer 1

You could create an extension method on XmlNode, like so:

public static class ExtensionMethods
{
    public string GetNodeText(this XmlNode node, string xPath)
    {
        var childNode = node.SelectSingleNode(xPath);
        return (childNode == null)
            ? "" : childNode.InnerText;
    }
}

searchResults.SearchResultCollection.Add(
    new SearchResult()
        {
            Header = HttpUtility.HtmlDecode(
                    htmlDocument.DocumentNode.GetNodeText(initialXPath + "h3"),
            Link = HttpUtility.HtmlDecode(
                    htmlDocument.DocumentNode.GetNodeText(initialXPath + "div/cite")
        }
    );

Personally, I’d probably just suck it up and put in the null tests explicityly, though 🙂