Retain values from dynamically created table with controls

Posted on 2004-11-01
Last Modified: 2008-03-03
I have a WebControls.Table that users are able to Add rows to using an Add button.  When the button is clicked, a new table row is created with several controls.  I am using a session variable to retain an arraylist of my table rows so that I can recreate the table on postback.  My issue is, that although the table is recreated, any data that my user may have typed in is gone - it appears the ViewState is not being maintained.

Here is some of my code:
            private void BtnAddBM_Click(object sender, System.EventArgs e)
                  //Add row table - get existing rows
                  newRows = (ArrayList)Session["newRows"];

                  //set rcount to initial row id - we have two header rows, so first row is 2
                  int rcount = 2 + newRows.Count;

                  //Create a new row
                  TableRow newRow = new TableRow();
                  newRow.ID = "nr" + rcount.ToString();
                  //Add cells
                  newRow.Cells.Add(new TableCell());
                  newRow.Cells.Add(new TableCell());
                  newRow.Cells.Add(new TableCell());
                  //Add the controls to the new row
                  newRow.Cells[0].HorizontalAlign = HorizontalAlign.Center;
                  newRow.Cells[1].HorizontalAlign = HorizontalAlign.Center;
                  newRow.Cells[2].HorizontalAlign = HorizontalAlign.Center;
                  newRow.Cells[3].HorizontalAlign = HorizontalAlign.Center;
                  newRow.Cells[4].HorizontalAlign = HorizontalAlign.Center;
                  newRow.Cells[5].HorizontalAlign = HorizontalAlign.Center;
                  newRow.Cells[6].HorizontalAlign = HorizontalAlign.Center;
                  newRow.Cells[7].HorizontalAlign = HorizontalAlign.Center;
                  newRow.Cells[8].HorizontalAlign = HorizontalAlign.Center;

                  //Store the new row in the array list

                  //Store the updated array list in session object
                  Session["newRows"] = newRows;

                  //Add all the rows created dinamicly to the table
                  foreach(TableRow currentRow in newRows)


How can I retain the values in these controls between PostBacks?



Question by:a222493
    LVL 6

    Expert Comment

    Remember with dynamic controls, they should be created each time the page loads. And also remember that neither the controls, nor their properties are available on the postback, because page has no way of knowing these controls on the postback, until they are recreated, that means the client changes are gone.
    LVL 8

    Expert Comment

    the problem with dynamica controls is that you must recreate them at every post back....

    everyone faces this problem with Dynamic controls
    LVL 8

    Accepted Solution

    to retain your viewstate, add your control on before checking for your post back.

     Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
            Dim txt As New TextBox()
            txt.ID = "MyTextBoxID"
            plchldr.Controls.Add(txt)             ''''' Add your control here instead of after the end if...

            If Not IsPostBack Then
                txt.Text = "Hello"
                txt.BackColor = Color.Yellow
            End If
    end sub

    check this link for detail discussion on the above issue....

    Load the controls on every post back

       Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
            'Put user code to initialize the page here
            If viewstate("Add") = "True" Then            ''''Check if the Link Buttons have already been created
            End If
        End Sub

    Sub Adddata()
            'Get a list of the categories
            '2. Create the command object, passing in the SQL string
            Dim strSQL As String
            strSQL = "SELECT catno,catname from category"
            Dim myCommand As OleDbCommand = New OleDbCommand(strSQL, OleDbConnection1)

            'Set the datagrid's datasource to the datareader and databind
            Dim myDataReader As OleDbDataReader = myCommand.ExecuteReader()

            'Loop through the results, creating a LinkButton for each row
            Dim filterButton As LinkButton
            While myDataReader.Read()
                'Add the LinkButton

                filterButton = New LinkButton()
                filterButton.ID = myDataReader("CatNo")
                filterButton.Text = myDataReader("CatName")
                filterButton.CommandArgument = myDataReader("catno")
                AddHandler filterButton.Command, AddressOf Me.FilterData


            End While


           viewstate("Add") = True
        End Sub

        Sub FilterData(ByVal sender As Object, ByVal e As CommandEventArgs)
           '''Code for handling event
        End Sub

    Also check this for detailed info....
    everyone faces this problem with Dynamic controls

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