Converting a string to an HTML document

Question

is there a way to put a string variable into a new declared htmldocument variable without going through a webbrowser ? i tried this

Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
    Dim v As New WebClient
    Dim page As String = ""
    Dim ahtm As HtmlDocument = Nothing

    page = v.DownloadString("http://www.google.com")
    ahtm.Body.InnerText = page                              'not working
    ahtm.Write(page)                                        'not working neither

End Sub

Can you elaborate on what you mean by not working? Is it throwing an exception or simply returning null? — Aelphaeis
– Aelphaeis, Commented Jun 27, 2014 at 18:15
it's throwing this exception An unhandled exception of type 'System.NullReferenceException' occurred in WindowsApplication6.exe — user3781458
– user3781458, Commented Jun 27, 2014 at 18:17
From the docs for HtmlDocument: "You obtain an instance of HtmlDocument through the Document property of the WebBrowser control." So, no, you can't do it without a WebBrowser control. Note that you don't have to actually display the WebBrowser control. What is the ultimate aim of this? — Andrew Morton
– Andrew Morton, Commented Jun 27, 2014 at 18:49

aban-developer · Accepted Answer · 2016-01-02 16:25:27Z

3

You can use WebBrowser without Navigate().

Public Function CreateDocument(ByVal url As String) As HtmlDocument
      Dim wb As New WebBrowser()
      wb.DocumentText=New WebClient().DownloadString(url)
      Return wb.Document
End Function

answered Jan 2, 2016 at 16:25

aban-developer

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1 Comment

Tyler Montney Over a year ago

In single threaded applications, sure. Otherwise, you're going to get an STA exception.

Aelphaeis · Accepted Answer · 2014-06-27 18:40:11Z

1

The reason is because you declared ahtm as Nothing. instantiate it and see if it works.

Update: HtmlDocument is a wrapper around an unmanaged class (IHtmlDocument). Try Declaring a WebBrower and then assigning the ahtm to the web browser document property.

WebBrowser wb = new WebBrowser();
HtmlDocument atm = wb.Document;

In other words, Web browser is the easiest way.

Update: The alternative would be to use something like HtmlAgilityPack. http://htmlagilitypack.codeplex.com/

edited Jun 27, 2014 at 18:40

answered Jun 27, 2014 at 18:18

Aelphaeis

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3 Comments

user3781458 Over a year ago

when i try to do that, it says "System.Windows.Forms.HtmlDocument' has no constructors"

user3781458 Over a year ago

as i said i need to do this without going through a webbrowser

user3781458 Over a year ago

thank you, that actually helped with the htmldocument.loadhtml

carla · Accepted Answer · 2017-12-15 13:24:12Z

0

Try the HTMLAgility Pack.

You can read about it here: http://html-agility-pack.net/

The latest version is available via NuGet.

So you would do something like:

Dim aHTML As New HTMLDocument
aHTML.Load(some string variable)

Note that you cannot load a URL in this fashion. I'm not sure if you really want to load a URL or if the URL provided was just for reference.

edited Dec 15, 2017 at 13:24

carla

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answered Jul 17, 2014 at 18:08

Mike Feltman

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1 Comment

Paul Seeb Over a year ago

Could you reference anything specifically related to the question?

Tyler Montney · Accepted Answer · 2018-02-05 19:15:22Z

Make sure to add a reference to Microsoft.mshtml.

    Private Function GetStatus(ByVal HTMLString As String) As mshtml.HTMLDocumentClass
          Dim htmlDocument As mshtml.IHTMLDocument2 = New mshtml.HTMLDocumentClass()
          htmlDocument.clear()
          htmlDocument.write(HTMLString)
          htmlDocument.close()

          Return htmlDocument
    End Function

You very well could try the HTMLAgility pack, but that's third party. I feel it's better to attempt using what's built in (unless third party is vastly superior in functionality and/or security). Then you have to worry about licensing and updates. Using Windows.Forms.WebBrowser will work too, unless you're multi-threading. I'm sure you could work it out, but it felt too complicated for my needs.

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