GetElementsByTagName in Htmlagilitypack

Question

How do I select an element for e.g. textbox if I don't know its id?

If I know its id then I can simply write:

HtmlAgilityPack.HtmlNode node = doc.GetElementbyId(id);

But I don't know textbox's ID and I can't find GetElementsByTagName method in HtmlagilityPack which is available in webbrowser control. In web browser control I could have simply written:

HtmlElementCollection elements = browser[i].Document.GetElementsByTagName("form");
foreach (HtmlElement currentElement in elements)
{

}

EDIT

Here is the HTML form I am talking about

<form id="searchform" method="get" action="/test.php">
<input name="sometext" type="text">
</form>

Please note I don't know the ID of form. And there can be several forms on same page. The only thing I know is "sometext" and I want to get this element using just this name. So I guess I will have to parse all forms one by one and then find this name "sometext" but how do I do that?

Solution 1

If you're looking for the tag by its tagName (such as form for <form name="someForm">), then you can use:

var forms = document.DocumentNode.Descendants("form");

If you're looking for the tag by its name property (such as someForm for <form name="someForm">, then you can use:

var forms = document.DocumentNode.Descendants().Where(node => node.Name == "formName");

For the last one you could create a simple extension method:

public static class HtmlNodeExtensions
{
    public static IEnumerable<HtmlNode> GetElementsByName(this HtmlNode parent, string name)
    {
        return parent.Descendants().Where(node => node.Name == name);
    }

    public static IEnumerable<HtmlNode> GetElementsByTagName(this HtmlNode parent, string name)
    {
        return parent.Descendants(name);
    }
}

Note: You can also use SelectNodes and XPath to query your document:

var nodes = doc.DocumentNode.SelectNodes("//form//input");

Would give you all inputs on the page that are in a form tag.

var nodes = doc.DocumentNode.SelectNodes("//form[1]//input");

Would give you all the inputs of the first form on the page

Solution 2

Any node by name:

doc.DocumentNode.SelectNodes("//*[@name='name']")

Input nodes by name:

doc.DocumentNode.SelectNodes("//input[@name='name']")

Solution 3

I think you are looking for something like this

HtmlAgilityPack.HtmlDocument doc = new HtmlAgilityPack.HtmlDocument();
doc.LoadHtml("....");

var inputs = doc.DocumentNode.Descendants("input")
    .Where(n => n.Attributes["name"]!=null && n.Attributes["name"].Value == "sometext")
    .ToArray();

Comments

[shriek]

well, what does the html look like? there might be another way.

[Ali]

@shriek I have edited my question please have a look.

[TFD]

See stackoverflow.com/a/3120867/68607

[jessehouwing]

No need for the n.Attributes checks and all. There's a Name property. You can use .Where(n => n.Name == TheNameYoureLookingFor);

[L.B]

@jessehouwing while i was preparing the answer, OP hadn't edited the question and the attribute was unknown.

[L.B]

@jessehouwing No I won't think of it too much for just a few lines of html OP has shown. I just showed the way and don't think to write OP's full code.

[jessehouwing]

I prefer to give complete and concise answers to prevent having to answer 10 new questions.

[L.B]

@jessehouwing I can not say that I am much interested in how you answer the questions. If you have something better to say than write as an answer. This is my way.