转发器ondatabinding事件中的ASP.NET Dropdownlist

Question

我在网上浪费了3-4个小时后才找到解决问题的方法。

现在我有一个转发器A，里面有一个下拉，一个TextBox和一个LinkBut​​ton，说添加更多。

单击该按钮，转发器的数据将保存到ViewState中，并添加一个新行并恢复ViewState数据。

现在，虽然恢复了TextBox中的数据，但下拉列表始终设置为空白。

aspx页面

<asp:Repeater runat="server" ID="POTaxDetails" OnItemCreated ="POTaxDetails_OnItemCreated" OnItemCommand="POTaxDetails_OnItemCommand" >
    <HeaderTemplate>
        <tr>
            <td colspan="2" class="tdDataDisp">
            </td>
            <td class="tdDataDisp">
                <asp:Label ID="LbTaxTypeText" runat="server" Text="Tax Type" CssClass="LbTblDataDisp"
                    Font-Bold="true"></asp:Label>
            </td>
            <td class="tdDataDisp">
                <asp:Label ID="LbTaxAmount" runat="server" Text="Tax Amount" CssClass="LbTblDataDisp"
                    Font-Bold="true"></asp:Label>
            </td>
            <td>
            </td>
        </tr>
    </HeaderTemplate>
    <ItemTemplate>
        <tr>
         <td colspan="2" class="tdDataDisp">
            <td class="tdDataDisp">
                <asp:DropDownList ID="TaxTypeList" runat="server" CssClass="LbTblDataSelect" OnDataBinding="TaxTypeList_OnDataBinding" AutoPostBack="true" >
                    <asp:ListItem Value="">----Select----</asp:ListItem>
                </asp:DropDownList>

            </td>
            <td class="tdDataDisp">
                <asp:TextBox ID="TaxAmount" runat="server" amtType="baseamount" expID="" taxType=""
                    CssClass="tblDataInput"></asp:TextBox>
            </td>
            <td class="tdDataDisp">
                <asp:LinkButton ID="btnRemove" runat="server" CommandName="remove" >Remove This</asp:LinkButton>
                &nbsp;
                 <asp:LinkButton ID="btnAddMore" runat="server" CommandName="addmore" >Add More</asp:LinkButton>
            </td>
        </tr>
    </ItemTemplate>
</asp:Repeater>

cs code

protected void POTaxDetails_OnItemCommand(object source, RepeaterCommandEventArgs e)
{
    //Repeater rp = e.CommandSource
    RepeaterItem rpItem = e.Item as RepeaterItem;
    Repeater rp = rpItem.NamingContainer as Repeater;

    if (e.CommandName == "addmore")
    {
        int rowIndex = 0;
        if (ViewState["CurrentTable"] != null)
        {
            DataTable dtCurrentTable = (DataTable)ViewState["CurrentTable"];
            DataRow drCurrentRow = null;
            if (dtCurrentTable.Rows.Count > 0)
            {
                for (int i = 1; i <= dtCurrentTable.Rows.Count; i++)
                {
                    DropDownList ddl = rp.Items[rowIndex].FindControl("TaxTypeList") as DropDownList;
                    TextBox tb = rp.Items[rowIndex].FindControl("TaxAmount") as TextBox;


                    drCurrentRow = dtCurrentTable.NewRow();
                    dtCurrentTable.Rows[i - 1]["TaxType"] = ddl.SelectedValue;
                    //taxlist = "";
                    if (taxlist == "")
                    {
                        taxlist = "'" + ddl.SelectedValue + "'";
                    }
                    else
                    {
                        taxlist += "," + "'" + ddl.SelectedValue + "'";
                    }
                    dtCurrentTable.Rows[i - 1]["TaxAmount"] = tb.Text;
                   // ClientScript.RegisterStartupScript(GetType(), "hwa", "alert('" + dtCurrentTable.Rows[i - 1]["TaxType"] + " - Hello World');", true);
                    rowIndex++;

                }
                dtCurrentTable.Rows.Add(drCurrentRow);

                ViewState["CurrentTable"] = dtCurrentTable;
                rp.DataSource = dtCurrentTable;
                rp.DataBind();

            }



        }

        rowIndex = 0;
        if (ViewState["CurrentTable"] != null)
        {

            DataTable dt = (DataTable)ViewState["CurrentTable"];
            if (dt.Rows.Count > 0)
            {
                for (int i = 0; i < dt.Rows.Count; i++)
                {
                    DropDownList taxType = (DropDownList)rp.Items[rowIndex].FindControl("TaxTypeList");
                    TextBox tb = (TextBox)rp.Items[rowIndex].FindControl("TaxAmount");

                    //Disable previous rows
                    if (i < dt.Rows.Count - 1)
                    {
                        taxType.Enabled= false;
                        tb.Enabled = false;

                    }
                    else
                    {
                        taxType.Enabled = true;
                        tb.Enabled = true;
                    }

                    taxType.SelectedValue = dt.Rows[i]["TaxType"].ToString();

                    ClientScript.RegisterStartupScript(GetType(), "hwa", "alert('" + dt.Rows[i]["TaxType"].ToString() + " - Bye World');", true);
                    tb.Text = dt.Rows[i]["TaxAmount"].ToString();
                    rowIndex++;
                }
            }
        }

    }

}

protected void TaxTypeList_OnDataBinding(object sender, System.EventArgs e)
{
  DropDownList ddl1 = (DropDownList)(sender);
    var firstitem = ddl1.Items[0];

    ddl1.Items.Clear();
    ddl1.Items.Add(firstitem);

    String selectCmd = "";
    if (taxlist == "")
    {
        selectCmd = "SELECT * from T_Tax_Type";

    }
    else
    {
        selectCmd = "SELECT * from T_Tax_Type where TaxID not in (" + taxlist + ")";

    }

    Repeater rp = ddl1.NamingContainer.NamingContainer as Repeater;
    int cnt = rp.Items.Count;

    SqlCommand myCommand = new SqlCommand(selectCmd, myConnection);

    SqlDataReader reader;
    reader = myCommand.ExecuteReader();

    if (reader.HasRows)
    {
        while (reader.Read())
        {
            ddl1.Items.Add(new ListItem(reader.GetString(1), reader.GetString(0)));
        }

    }
    reader.Close();
    ddl1.SelectedValue = "";
}

protected void bindTaxList(Repeater rp, string taxList)
{
    try
    {
        DataTable dt = new DataTable();
        DataRow dr = null;

        //Create DataTable columns
        dt.Columns.Add(new DataColumn("TaxType", typeof(string)));
        dt.Columns.Add(new DataColumn("TaxAmount", typeof(string)));
      //  dt.Columns.Add(new DataColumn("Comments", typeof(string)));
                dr = dt.NewRow();
                dr["TaxType"] = string.Empty;
                dr["TaxAmount"] = string.Empty;
                dt.Rows.Add(dr);

        rp.DataSource = dt;
        rp.DataBind();

        ViewState["CurrentTable"] = dt;
    }
    catch (Exception ex)
    {
    }
}

现在我认为只有前两个函数之间存在一些问题。第三个功能是我第一次绑定转发器的方式。