[RESOLVED] Webbrowser class problem [VS2005 .NET 2.0]

[Krenshau]

Hello,

I am having a problem with some code I putting together. I am trying to implement a webbrowser class, without using the webbrowser control on a form. I want to navigate to a page, determine if the page is loaded, then extract the link collection and display them in a text box on a form.

Here is my code.

Dim I As Integer = 1
        Dim WB As New WebBrowser
 
        WB.Navigate(Me.URL.Text.Trim.ToString)
 
        If (Not (WB.Document Is Nothing)) Then
            Dim HDoc As HtmlElementCollection = WB.Document.Links
 
            For I = 1 To HDoc.Count
                Me.PageText.Text = Me.PageText.Text & HDoc.Item(I).ToString & vbCrLf
            Next
        End If

The problem I am having is that it says the WB.Document is nothing. Am I missing something? I am just learning .NET and this is the first time doing this, so I am not sure what I am missing. I have looked at MSDN, and done some googling, but don't see anything similar to what I am doing. Everyone else tries to use regex, but I think this would be better, if I can figure out how to do it.

Thank you for your help.

[VBDT]

try to use this

Public Class Form1
 
    Dim WithEvents WB As New WebBrowser
 
    Private Sub WB_DocumentCompleted(ByVal sender As Object, ByVal e As System.Windows.Forms.WebBrowserDocumentCompletedEventArgs) Handles WB.DocumentCompleted
        Dim I As Integer = 1
        If Me.WB.Document.Links.Count <> 0 Then
            'do what ever
        End If
    End Sub
End Class

Edit **

[ComputerJy]

Try this:

Private Sub getLinks()
        Dim I As Integer = 1
        Dim WB As New WebBrowser
        AddHandler WB.DocumentCompleted, AddressOf DocumentCompleted
        WB.Navigate(Me.URL.Text.Trim.ToString)
    End Sub
    Private Sub DocumentCompleted(ByVal sender As Object, ByVal e As System.Windows.Forms.WebBrowserDocumentCompletedEventArgs)
        Dim wb As WebBrowser = CType(sender, WebBrowser)
        If wb.Document IsNot Nothing Then
            Dim HDoc As HtmlElementCollection = wb.Document.Links
            For Each link As String In HDoc
                Me.PageText.Text += link + ControlChars.NewLine
            Next
        End If
    End Sub

[Krenshau]

That worked, thank you very much.

[Krenshau]

Thank you for helping me before. I need some more help, though.

I am trying to get the adapt the code from above to be used in a class. I think it is possible, but I can't figure out how to do this. I think I have to convert this collection that is returned into an array, then pass that array out of the function to the other function, then out of that function to the calling client.

Here is my code.

Public Function GetPageHrefs(ByVal URL As String) As String()
        Try
            AddHandler WB.DocumentCompleted, AddressOf DocumentReady
            WB.Navigate(URL)
        Catch ex As Exception
            Dim I(1) As String
            I.SetValue(ex.ToString, 1)
            Return I
        End Try
    End Function
 
    Private Function DocumentReady(ByVal sender As Object, ByVal e As System.Windows.Forms.WebBrowserDocumentCompletedEventArgs) As String()
        Dim WB As System.Windows.Forms.WebBrowser = CType(sender, System.Windows.Forms.WebBrowser)
        If WB.Document IsNot Nothing Then
            Dim HDoc As System.Windows.Forms.HtmlElementCollection = WB.Document.Links
            Return HDoc
        End If
    End Function

If someone can point me in the right direction on doing this, I would be grateful. Also, can someone tell me if the way I shoot the error message out in the first function will work?

Thank you for your help.

[jmcilhinney]

If you don't want to display a Web page then you shouldn't be using the WebBrowser control at all. Use the WebClient class instead, which doesn't have the overhead of the control that you will never make use of anyway. The WebClient.DownloadString method will retrieve the source code for a Web page to a String object, which you can then parse to extract the parts you need. If you want just the links then there are numerous examples about of using regular expressions to do so.

[Krenshau]

Thank you for your suggestion, but I don't want to use regular expression. This is more accurate. I have used regular expressions, and they are great for many things, but I prefer the webbrowser for this purpose, I just haven't used it in a class situation where I had to move the data around like this. I don't care about overhead in this situation, either.

Also, I am going to be creating different functions to extract many different attributes, not just the href. They will use this same pattern, once I figure out the method.

[Krenshau]

I am setting this to resolved. I have to rethink how this will work because the sub that gets called finishes after it passes the url to the webbrowser, this doesn't allow the data from the document complete to be passed back to the client. Since I can't use an even to pass it back to the client, I will have to rethink this.

Thank you for your help.