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Help with loading data in dropdownlist of a web form

Hello,

I am able to load my dropdown list in my Windows application. However when I transfer the code to my ASP.NET application. The program doesn't understand the properties where the Error line is listed (DisplayMember, ValueMember ). Which properties do 'i need to replace them with for the web application?

code:
Dim lnk As XmlNodeList = LinkStream.SelectNodes("Root/Link")
Dim RecName As XmlNodeList = RecStream.SelectNodes("Root/Receiver")
Dim DonorName As XmlNodeList = DonorStream.SelectNodes("Root/Donor")

Dim donorlst As New DataTable()
donorlst.Columns.Add("ID")
donorlst.Columns.Add("Name")
Dim reclst As New DataTable
reclst.Columns.Add("ID")
reclst.Columns.Add("Name")

For Each n As XmlNode In lnk
Dim rID As Integer = Val(n.ChildNodes(0).InnerText)
Dim dID As Integer = Val(n.ChildNodes(1).InnerText)

For Each node As XmlNode In RecName
If node.ChildNodes(0).InnerText = rID.ToString Then
reclst.Rows.Add(New Object() {rID, node.ChildNodes(1).InnerText})
'Exit For
End If
Next

For Each node As XmlNode In DonorName
If node.ChildNodes(0).InnerText = dID.ToString Then
donorlst.Rows.Add(New Object() {node.ChildNodes(0).InnerText, node.ChildNodes(1).InnerText})
'Exit For
End If
Next
Next

CmbDonor.DataSource = donorlst
CmbDonor.DisplayMember = "Name" *****Error
CmbDonor.ValueMember = "ID" ********Error

Thanks,

Victor

binaryevo

DataTextField and DataValueField. See below:

this.drop1.DataSource = Domain.DataEntity.LoadStuff();
                this.drop1.DataTextField = "TextValue";
                this.drop1.DataValueField = "IDValue";
                this.drop1.DataBind();

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Victor Charles

ASKER

Thanks for the code, I will get back to you tomorrow.

Victor Charles

ASKER

I tried modifying the code below but I receive the following error:

'CmbDonor' has a SelectedValue which is invalid because it does not exist in the list of items.
Parameter name: value

Code:
Dim DonorName As XmlNodeList = DonorStream.SelectNodes("Root/Donor")

Dim donorlst As New DataTable()
donorlst.Columns.Add("DonorID")
donorlst.Columns.Add("Name")

For Each node As XmlNode In DonorName
donorlst.Rows.Add(New Object() {node.ChildNodes(0).InnerText, node.ChildNodes(1).InnerText})
Next

CmbDonor.DataSource = donorlst
CmbDonor.DataTextField = "Name"
CmbDonor.DataValueField = "DonorID"
CmbDonor.DataBind()

Below is an example of Donor.xml

<?xml version="1.0" encoding="utf-8" standalone="yes"?>
<Root>
<Donor>
<DonorID>1</DonorID>
<Name>BEL</Name>
</Donor>
<Donor>
<DonorID>2</DonorID>
<Name>USA</Name>
</Donor>
<Donor>
<DonorID>3</DonorID>
<Name>CAN</Name>
</Donor>
<Donor>
<DonorID>4</DonorID>
<Name>DEU</Name>
</Donor>
<Donor>
<DonorID>5</DonorID>
<Name>HGH</Name>
</Donor>
</Root>

Thanks.

Victoir

binaryevo

I don't use datatables very often but I think the syntax goes something like this dataset.tables[0].rows[0][columnname]. So in your case instead of saying datatextfield and datavaluefield = columnname you would use the above syntax. I'm doing this from memory so you may need to play with the exact syntax a little bit. Give that a shot and let me know.

Victor Charles

ASKER

I'm afraid the program doesn't understand the "Dataset", below is my code, can you please show me how you would modify it to use the code you are proposing.

Public Sub FillCombos()
Dim DonorName As XmlNodeList = DonorStream.SelectNodes("Root/Donor")

Dim donorlst As New DataTable()
donorlst.Columns.Add("DonorID")
donorlst.Columns.Add("Name")

For Each node As XmlNode In DonorName
donorlst.Rows.Add(New Object() {node.ChildNodes(0).InnerText, node.ChildNodes(1).InnerText})
Next

CmbDonor.DataSource = donorlst

CmbDonor.DataTextField = "Name"
CmbDonor.DataValueField =
CmbDonor.DataBind()
End Sub

Thanks,

Victor

binaryevo

CmbDonor.DataSource = donorlst

CmbDonor.DataTextField = donorlst.rows(0)("name")
CmbDonor.DataValueField = donorlst.rows(0)("id")
CmbDonor.DataBind()

Try that!

Victor Charles

ASKER

I don't know why I'm getting this error message:

DataBinding: 'System.Data.DataRowView' does not contain a property with the name 'CAN'.

Below is my xml files. Any ideas what is causing this error?

Donor:

<?xml version="1.0" encoding="utf-8" standalone="yes"?>
<Root>
<Donor>
<DonorID>1</DonorID>
<Name>BEL</Name>
</Donor>
<Donor>
<DonorID>2</DonorID>
<Name>USA</Name>
</Donor>
<Donor>
<DonorID>3</DonorID>
<Name>CAN</Name>
</Donor>
<Donor>
<DonorID>4</DonorID>
<Name>DEU</Name>
</Donor>
</Root>

Receiver:

<?xml version="1.0" encoding="utf-8" standalone="yes"?>
<Root>
<Receiver>
<ReceiverID>1</ReceiverID>
<Name>BEL</Name>
</Receiver>
<Receiver>
<ReceiverID>2</ReceiverID>
<Name>USA</Name>
</Receiver>
<Receiver>
<ReceiverID>3</ReceiverID>
<Name>CAN</Name>
</Receiver>
<Receiver>
<ReceiverID>4</ReceiverID>
<Name>DEU</Name>
</Receiver>
</Root>

Link:

<?xml version="1.0" encoding="utf-8" standalone="yes"?>
<Root>
<Link>
<LinkID>1</LinkID>
<ReceiverID>3</ReceiverID>
<DonorID>2</DonorID>
</Link>
<Link>
<LinkID>1</LinkID>
<ReceiverID>1</ReceiverID>
<DonorID>3</DonorID>
</Link>
<Link>
<LinkID>1</LinkID>
<ReceiverID>2</ReceiverID>
<DonorID>1</DonorID>
</Link>
</Root>

Thanks,

Victor

binaryevo

Its hard to telll without the source code but, usually an error like that indicates that you are trying to use the property / column "CAN" to bind to. Please check your code and ensure that you are in fact using DonorID and Name when you add the columns and DonorID and Name when you give the DataTextField and DataValueField.

Victor Charles

ASKER

I ran the program again and noticed, The error is occuring on the first "Name" element of Donor.xml

Error: DataBinding: 'System.Data.DataRowView' does not contain a property with the name 'Test'.

Any ideas what is causing the error on this line?

<?xml version="1.0" encoding="utf-8" standalone="yes"?>
<Root>
<Donor>
<DonorID>1</DonorID>
<Name>Test</Name> ***** Error Line
</Donor>
<Donor>
<DonorID>2</DonorID>
<Name>USA</Name>
</Donor>
<Donor>
<DonorID>3</DonorID>
<Name>CAN</Name>
</Donor>
<Donor>
<DonorID>4</DonorID>
<Name>DEU</Name>
</Donor>
</Root>

Victor

ASKER CERTIFIED SOLUTION

binaryevo

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Victor Charles

ASKER

Thanks for the code, it works but when I select a row from cmbDonor, the value selected is not registered, for example when I try to see the value selected in a meaasge box with the code below, I get the value of the first row, even when I set the Auto postback property to True.
MsgBox(CmbDonor.SelectedItem.ToString) Any ideas what I'm doing wrong?

Victor Charles

ASKER

I will ask the post follow up question as another post, will close this post.

Thanks,

Victor