To select all image> elements, use HTMLAgilityPack SelectNodes.

c# html html-agility-pack regex xpath


I am making a project in C# that's basically an image screen scraper for an image-search related game. I'm trying to use HTMLAgilityPack to select all the image elements and put them in an HTMLNodeCollection, like this:

//set up for checking autos

HtmlNodeCollection imgs = new HtmlNodeCollection(doc.DocumentNode.ParentNode);
imgs = doc.DocumentNode.SelectNodes("//img");

foreach (HtmlNode img in imgs)
    HtmlAttribute src = img.Attributes["@src"];

Note that urls is a public List collection:

public List<string> urls = new List<string>();

My foreach loop is throwing an exception:

Object reference not set to an instance of an object.

Checking the autos, sure enough, imgs is null. Is there any better way I can track down the source of this problem? I have no idea if it's my Xpath or what.

The most frustrating part is that I had already gotten it to work, but messed up my file versions and lost my work. Derp.

10/25/2011 12:31:46 AM

Accepted Answer

You might have a typo in the following line:

HtmlAttribute src = img.Attributes["@src"];

I got this to work for me (notice the @ position):

HtmlAttribute src = img.Attributes[@"src"];
2/1/2012 12:43:17 AM

Popular Answer

This works for me. I think your document isn't loaded correctly, hence the xpath returns no matches.

HtmlDocument htmlDocument = new HtmlDocument();
htmlDocument.LoadHtml("<html><head></head><body><div><img /><div><img /><img/></div></div><img/></body></html>");

var nodes = htmlDocument.DocumentNode.SelectNodes("//img");
// 4 nodes found
foreach (var node in nodes)
    // do stuff

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