Visual Basic

30-Sep-04 5:33

Hey,

I have a treeview in my vb.net application. when i change the name of my treenode i am trying to reflect the change in my xml document and then repopulate the tree.

<category>
<name>Data To be Updated</name>
</category>

I can populate tree view, and rename the tree node but am unable to reflect the change in the xml

Any help would be greatly appreciated i have tried looking at examples but and unable to get anywhere.

thanks for any help in advance

Dave Kreskowiak30-Sep-04 11:08

30-Sep-04 11:08

How is your Treeview bound to the XML? Is it through a DataSet or is the TreeView just loading it from the .XML file directly?

The only way you can do something like this is if your Treeview is bound to a DataSet version of the XML file. When the data is changed in the Treeview, the DataSet can be updated. When the changes are complete, the DataSet can export back to an XML file. The Treeview control CANNOT do this.

RageInTheMachine9532
"...a pungent, ghastly, stinky piece of cheese!" -- The Roaming Gnome

cwayman30-Sep-04 22:13

30-Sep-04 22:13

Hey,

I populate my tree using a recursive function to load hte xml file, and can add nodes to the tree which update the xml file using MSXML. Can i use MSXML to update the data between tags in the XML file:

<category>
<name>Data To be Updated</name>
</category>

(the tree node names) based on the selected tree node being renamed using the AfterLabelEdit command?

Thanks for the help Smile | :)

Chris

Dave Kreskowiak1-Oct-04 2:39

1-Oct-04 2:39

Well, since the TreeView control doesn't support Data Binding, you'll either have to add that support by creating a custom TreeView control or use a similar procedure to write the data back out that you used to get it into the TreeView.

You'll have to do some extra research on these methods to see what's going to work the best for your situation and requirements.

You might want to take a look at Extending the TreeView Control[^] on MSDN for a how-to on adding Data Binding.

When you rename a node in the Tree, the TreeView will fire a couple of events. You use the source data to find the appropriate node in the DataSet and update the data in the DataSet. Now, when your done, the DataSet object can write the resulting XML file back out for you. You won't have to iterate through the nodes and write eash one out by hand. That's why I highly suggest you use a DataSet object for your Tree data source.

RageInTheMachine9532
"...a pungent, ghastly, stinky piece of cheese!" -- The Roaming Gnome

cwayman1-Oct-04 3:19

1-Oct-04 3:19

Thanks for your input, appreciate it.

I have managed to load the xml file in to a dataset before, but was unable to make the treeview use this dataset.

I will read that article and let you know how i get on.

Thanks again

Chris

cwayman4-Oct-04 3:30

4-Oct-04 3:30

Hey Dave,

I have written a function that can update the xml file using a DataSet.

My problem is I call this function in the AfterLabelEdit method and it runs.

But it updates the old name with the old name! as i cannot catch the new name that is typed in to the selected treenode until the AfterLabelEdit method as finished.

Do you have any suggestions of how to get the newly type name so when enter is pressed and the AfterLabelEdit method is run the new name can be used to update the old one using the update dataset function.

Thanks you for your help

Chris

Dave Kreskowiak4-Oct-04 11:00

4-Oct-04 11:00

What's the code in the event handler? Are you using the .Text property of the e.Node object that's passed to the handler? You will get the Node that was edited in the e.Node object AND you will get the new label text in the e.Label object.

RageInTheMachine9532
"...a pungent, ghastly, stinky piece of cheese!" -- The Roaming Gnome

cwayman5-Oct-04 5:34

5-Oct-04 5:34

Hey,

Cheers again for the help, i have used a timer and made the AfterSelectEvent fire that. But will be changing my treenode to use a real dir structure soon, so i will keep that in mind thankyou.

Another question is that i am now using DSOFile to load MS Office file properties in to the form when the file node of my tree is double clicked.

This works and loads the file properties in to the form first time the node is double clicked, but if you try to go back to that file an error occurs saying that it cannot load the file properties because the file is open.

Is there anyway to close the file as soon as the properties have been retrieved?

Thank you for all your help

Chris

Dave Kreskowiak5-Oct-04 12:25

5-Oct-04 12:25

You can force the release of the underlying COM object by using Marshal.ReleaseComObject() on the instance of the DSO object you created. Try this:

Imports System.Runtime.Interop
.
.
.
    '  I'm assuming you're using the PropertyReadClass...
    Dim dso As New DSOleFile.PropertyReaderClass
    '
    '  Do whatever you need to with the object here...
    '
    ' Now, release the unmanaged object and it's underlying resources.
    Marshal.ReleaseComObject(dso)
    ' Drop our managed reference to the object.
    dso = Nothing
.
.
.

And let the garbage collector do the rest...

RageInTheMachine9532
"...a pungent, ghastly, stinky piece of cheese!" -- The Roaming Gnome

cwayman5-Oct-04 22:13

5-Oct-04 22:13

Hey,

Thanks for the reply. I have tried using the Marshal.ReleaseComObject but it does not seem to close the file, giving the error 'The file is open and cannot be read'. I have used hte import of InteropServices too.

my code is:

<br />
            'DSO Properties<br />
            Dim oDsoPropReader As DSOleFile.PropertyReader = New DSOleFile.PropertyReaderClass<br />
            Dim oDsoFileProp As DSOleFile.DocumentProperties<br />
<br />
            oDsoFileProp = oDsoPropReader.GetDocumentProperties(strFullPath) '<-- This line causes the error<br />
<br />
            tbAuthor.Text = oDsoFileProp.Author<br />
            tbFormat.Text = oDsoFileProp.AppName<br />
            lblDateCreated.Text = oDsoFileProp.DateCreated<br />
            lblDateModfied.Text = oDsoFileProp.DateLastSaved<br />
<br />
            Marshal.ReleaseComObject(oDsoPropReader)<br />
<br />
            oDsoFileProp = Nothing<br />
            oDsoPropReader = Nothing<br />

Is my code wrong?, this help is really appreciated.

Chris

cwayman6-Oct-04 0:00

RE: Automate code-writing in VB.NET control's development

6-Oct-04 0:00

I have solved hte problem i also released the DocumentProperties as well as the reader, thanks for all your help Dave.

Chris

esalkin30-Sep-04 2:54

esalkin

30-Sep-04 2:54

http://www.thecodeproject.com/vb/net/classinspector.asp[^]

This is a great little tool that can make implementing a snap.

There is a minor bug in the program that truncates some properties.
For instance, the Textbox property _PasswordChar has a default of Chr(0) which is a 'null.' The problem is that the textbox sees a null as an EOF and truncates the string. A simple solution is to remove the null char. To do this, change the line in showEnum and showControlProps from currentText = sb.ToString to read currentText = sb.ToString.Replace(Chr(0), "")

exception

Fired Dragon30-Sep-04 2:45

Fired Dragon

30-Sep-04 2:45

could anyone tell me why i've got this error message and how i can solve it?

thanks

Server Error in '/Log_In' Application.
--------------------------------------------------------------------------------

Specified cast is not valid.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.InvalidCastException: Specified cast is not valid.

Source Error:

Line 53: Loop
Line 54:
Line 55: DdlNoperiod.Items.AddRange(New Object() {"10", "11", "12", "13"})
Line 56:
Line 57: 'Put user code to initialize the page here

Source File: C:\Inetpub\wwwroot\Log_In\calendar.aspx.vb Line: 55

Stack Trace:

[InvalidCastException: Specified cast is not valid.]
Log_In.calendar.Page_Load(Object sender, EventArgs e) in C:\Inetpub\wwwroot\Log_In\calendar.aspx.vb:55
System.Web.UI.Control.OnLoad(EventArgs e)
System.Web.UI.Control.LoadRecursive()
System.Web.UI.Page.ProcessRequestMain()

Re: exception

Syed Abdul Khader30-Sep-04 3:44

Syed Abdul Khader

30-Sep-04 3:44

DdlNoperiod.Items.AddRange(New Object() {"10", "11", "12", "13"})

I think DdlNoperiod is DropDownList. You can add only ListItem() to the DropDownList using AddRange method.

Do like this.

DdlNoperiod.Items.AddRange(New Object() {new ListItem("10"), new ListItem("11"), new ListItem("12"), new ListItem("13") })

Re: exception

Fired Dragon30-Sep-04 12:27

Fired Dragon

30-Sep-04 12:27

unfortunately, it doesn't work by that way.

Convert from C#

LeeOvEngland30-Sep-04 2:23

LeeOvEngland

30-Sep-04 2:23

I have a function that I need to convert from C# to VB.

C#
public byte[] ConvertStreamToByteBuffer(System.IO.Stream theStream)
{
int b1;
System.IO.MemoryStream tempStream = new System.IO.MemoryStream();

while((b1=theStream.ReadByte())!=-1)
{
tempStream.WriteByte(((byte)b1));
}

return tempStream.ToArray();
}

My VB So far...
Public Function ConvertStreamToByteBuffer(ByVal theStream As System.IO.Stream) As Byte()
Dim b1 As Integer
Dim tempStream As New System.IO.MemoryStream

While ((b1 = theStream.ReadByte()) <> -1)
tempStream.WriteByte(((byte)b1))
End While

Return tempStream.ToArray()
End Function

i keep getting an error of: 'Byte' is a type, and so is not a valid expression. referring to the code in the while statement.

Please can someone help me to convert the function

Thank You

The Man from U.N.C.L.E.30-Sep-04 3:25

The Man from U.N.C.L.E.

30-Sep-04 3:25

You have only one error in the line tempStream.WriteByte(((byte)b1)). The VB equivelent of (byte)b1 is CType(b1, Byte).

The full VB code should be

Public Function ConvertStreamToByteBuffer(ByVal theStream As System.IO.Stream) As Byte()
	Dim b1 As Integer
	Dim tempStream As New System.IO.MemoryStream
	While Not ((b1 = theStream.ReadByte) = -1)
		tempStream.WriteByte(CType(b1, Byte))
	End While
	Return tempStream.ToArray
End Function

Gavin Jeffrey30-Sep-04 3:41

Gavin Jeffrey

30-Sep-04 3:41

here is a pretty cool site that converts vb to c# and vica versa - its not perfect it sure beats typing everything out -

http://www.developerfusion.com/utilities/convertvbtocsharp.aspx

The Man from U.N.C.L.E.30-Sep-04 7:05

The Man from U.N.C.L.E.

30-Sep-04 7:05

Personaly I use SharpDevelop[^] which has a built in C# to VB.Net and VB.Net to c# converter. I use it a lot as I write in VB.Net as work and C# at home. It is quicker to convert whole classes than to rewrite from scratch, even though the conversion is only 99% perfect.