Dynamic textbox error Collection was modified; enumeration operation

[Dashley]

Hi. I going thorough a datareader and at the same time dynamically creating text boxes and I'm getting an error Collection was modified; enumeration operation may not execute

What I'm trying to do is display a list of items (books).
Title, Author, price. I'm doing this with a datareader.

I want to add a textbox as the reader reads so they can enter the qty they want and then when the hit a button collect all the TB's that have a qty.

Problem is with creating the TB's

thanks

 

[jbenson001]

Where and how are you adding the textboxes? Can you show your code so we can help?

 

[Dashley]

Well I don't know if I made it better or worse. Now all the TB's are dumping out on the bottom of my form but I at least got past the error. How can I get them inside the "<td>" cell

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load

Dim cmd As New OleDbCommand
Dim DRClassics As OleDbDataReader

Dim conn As New OleDbConnection(System.Configuration.ConfigurationManager.AppSettings("connString"))
cmd.CommandText = ("Select author, title,isbn,price from books where active=0 and category='classics' and indx <= 20 order by author, title  ")
 cmd.Connection = conn
    conn.Open()

 DRClassics = cmd.ExecuteReader

Response.Write("<table border='1'>")

  Dim iSBN As String = Nothing
 Dim tb As TextBox
   While DRClassics.Read
                
    tb = New TextBox
    tb.ID = DRClassics("ISBN").ToString
                
    iSBN = DRClassics("isbn")
     Response.Write("<tr><td  width='250px' class='bodylist'>")
Response.Write("<font color='darkblue' size='1'>" & DRClassics(0))
Response.Write("<td width='250px'><font color='darkblue' size='1'>" & DRClassics("title"))
Response.Write("<td><font color='darkblue' size='1'>" & DRClassics("ISBN"))
Response.Write("<td><font color='darkblue' size='1'>")
.Write(DRClassics("Price"))
Response.Write("<td>")
form1.Controls.Add(tb)
            
 End While

  Response.Write("</table>")

 End Sub

 

[jbenson001]

First, using response.write to output to your page is bad practice. You should create the objects you need and add them to the page's controls collection.
Second, you don't need a datareader for this. A grid would be better or a repeater.

 

[sunila7]

Why are you not a using a repeater control to do this?

Try the code(not tested) below not sure if this code below will work.

     Response.Write("<tr><td  width='250px' class='bodylist'>")
Response.Write("<font color='darkblue' size='1'>" & DRClassics(0))
Response.Write("<td width='250px'><font color='darkblue' size='1'>" & DRClassics("title"))
Response.Write("<td><font color='darkblue' size='1'>" & DRClassics("ISBN"))
Response.Write("<td><font color='darkblue' size='1'>")
.Write(DRClassics("Price"))
form1.Controls.Add(tb)
Response.Write("<td></tr>")

Sunil

 

[Dashley]

Ok I'll go give the gridview a try. Can I just add an input fieldd to the grid.

 

[sunila7]

Yes you can add what ever controls you want in a grid view. Drop a GridView control on the page and look at the columns HTML tag inside it. You can have TemplatedFields which can contain any control you want.

Here is a link.

http://geekswithblogs.net/azamsharp/archive/2005/10/05/56183.aspx

Sunil

 

[Dashley]

cool, I already added the textbox. I might have te same probelm with giving it a different name though. I may be able to key of the isbn fies as its a unique number.


Taks

 <asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False" DataKeyNames="isbn"
            DataSourceID="AccessDataSource1" Width="555px">
            <Columns>
                <asp:BoundField DataField="author" HeaderText="author" SortExpression="author" />
                <asp:BoundField DataField="title" HeaderText="title" SortExpression="title" />
                <asp:BoundField DataField="isbn" HeaderText="isbn" ReadOnly="True" SortExpression="isbn" />
                <asp:BoundField DataField="price" HeaderText="price" SortExpression="price" />      
                <asp:TemplateField HeaderText="Qty"><ItemTemplate>
                <asp:TextBox ID="TextBox1" runat="server" Width="25" MaxLength="3"></asp:TextBox>
                   </ItemTemplate>
                </asp:TemplateField>
            </Columns>
            
        </asp:GridView>

 

[sunila7]

A control inside the gridview will get a ASP.Net generated name while HTML is being rendered. If you want to access the controls inside you will have to use FindControl method of GridViewRow.


Sunil

 

[Dashley]

Sunil

Ok I got it. Works great. Thank you very much,.

JB thanks for pointing me in the right direction.


-dan

 

[jbenson001]

cool.. glad you got it