how to maintain form control values after user control post back

Question

hello experts,

I have created filter grid in asp.net & C#.

My form design has contains 3 dropdown controls and Filter grid(User control).

Its working fine(filter), but one problem arise.

the form controls are clear when i filter a grid(post back).

I tried to reterive values using view state, hidden controls, i got only null values.

Anyone please help, its urgent to me.


Its my user control code.

FilterGrid.aspx

<%@ Control Language="C#" AutoEventWireup="true" CodeFile="FilterGrid.ascx.cs" Inherits="FilterGrid" %>

<style type = "text/css">

.cssPager td

{

border-left: white 1px solid;

padding-left: 4px;

padding-right: 4px;

padding-bottom:4px;

}

.cssHead th

{

border-left: white 1px solid;

padding-left: 4px;

padding-right: 4px;

padding-bottom:4px;

}

</style>

<script type="text/javascript" language="javascript">

//this method sets filter condition.

function filtergrid(path, columnname)

{

var val;

var baseurl;

baseurl = path;

val = document.getElementById('txt' + columnname).value;

self.location.href = baseurl + '?selectedcolumn=' + columnname + '&selectedvalue=' + val;

}

//this method removes filter condition.

function removefilter(path)

{

var baseurl;

baseurl = path;

self.location.href = baseurl;

}

</script>

 

<asp:datagrid id="ListGrid" runat="server" AutoGenerateColumns="false" AllowPaging="true" CssClass="cssPager" Font="verdana"

Font-Size="15px" GridLines="Vertical" BorderColor="Transparent" BorderStyle="None" Width="100%" OnPageIndexChanged="ListGrid_PageIndexChanged" PageSize="15">

<SelectedItemStyle BackColor="#C0C0FF" />

<PagerStyle HorizontalAlign="Left" VerticalAlign="Middle" NextPageText="" PrevPageText="" Mode="NumericPages" />

<AlternatingItemStyle BackColor="#D2D8DE" />

<ItemStyle BackColor="White" HorizontalAlign="Left" />

<HeaderStyle BackColor="#467DA0" CssClass="cssHead" ForeColor="White" Font-Bold="True" HorizontalAlign="Center" VerticalAlign="Middle"/>

</asp:datagrid>

FilterGrid.aspx.cs

using System;

using System.Data;

using System.Configuration;

using System.Collections;

using System.Web;

using System.Web.Security;

using System.Web.UI;

using System.Web.UI.WebControls;

using System.Web.UI.WebControls.WebParts;

using System.Web.UI.HtmlControls;

using Utilities;

public partial class FilterGrid : System.Web.UI.UserControl

{

#region " Properties and Instance Variables "

private string _FilterColumnName;

private string _FilterValue;

private string[] _ColumnNames;

private string[] _DisplayColumnNames;

string _path = string.Empty;

DataTable dtGrid = new DataTable();

clsGridFilter objFilter = new clsGridFilter();

#endregion

protected void Page_Load(object sender, EventArgs e)

{

}

public void BindData(string path, DataTable dtTable, string[] columnNames, string[] DisplayNames)

{

ListGrid.Columns.Clear();

_ColumnNames = columnNames;

_DisplayColumnNames = DisplayNames;

_path = path;

dtGrid = dtTable;

//initialization method

MyInit();

DataView listView = default(DataView);

listView = FilterDataSource(dtTable);

if ((listView != null))

{

FillDataGridColumns(path, listView.Table, _ColumnNames, _DisplayColumnNames);

}

ListGrid.DataSource = listView;

ListGrid.DataBind();

}

//initialization method

private void MyInit()

{

SetQueryParameters();

}

//Sets the instance variables

private void SetQueryParameters()

{

_FilterColumnName = Request.QueryString["selectedcolumn"];

_FilterValue = Request.QueryString["selectedvalue"];

}

//Filters Datasource

private DataView FilterDataSource(DataTable ListTable)

{

//Dataview Row Filter based on querystring

//This example handles "String","Double" datatypes and can be expanded to any other datatypes.

DataView tempView = new DataView(ListTable);

if ((_FilterColumnName != null) & (_FilterValue != null))

{

switch (ListTable.Columns[_FilterColumnName].DataType.ToString().ToUpper())

{

case "SYSTEM.STRING":

//for strings - "Like 'xxx%'"

tempView.RowFilter = "[" + _FilterColumnName + "] Like '" + _FilterValue + "%'";

break;

case "SYSTEM.DOUBLE":

//for numeric values - "= condition"

tempView.RowFilter = "[" + _FilterColumnName + "] = " + _FilterValue;

break;

case "SYSTEM.DECIMAL":

if (_FilterValue != "")

{

tempView.RowFilter = "[" + _FilterColumnName + "] = " + _FilterValue;

}

break;

case "SYSTEM.DATETIME":

if (_FilterValue != "")

{

tempView.RowFilter = "[" + _FilterColumnName + "] = " + _FilterValue;

}

break;

}

}

return tempView;

}

private void FillDataGridColumns(string path, DataTable ListTable, string[] ColumnNames, string[] DisplayNames)

{

int i = 0;

string headerhtml = null;

// int InCollectionIndx = 0;

ListGrid.AutoGenerateColumns = false;

if ((ColumnNames != null))

{

if ((ListTable != null))

{

for (i = 0; i <= ColumnNames.Length - 1; i++)

{

headerhtml = null;

if (ColumnNames[i].Trim().Length > 0)

{

if (ListTable.Columns.Contains(ColumnNames[i]))

{

BoundColumn x = new BoundColumn();

//set Column DataField

x.DataField = ColumnNames[i];

//set Header Display

if ((DisplayNames != null))

{

if (DisplayNames.Length > i)

{

if (DisplayNames[i].Trim().Length > 0)

{

//Header with textbox and go button

headerhtml = DisplayNames[i];

headerhtml = headerhtml + " <br> " + "<Input type=text style=width:70px;height:15px class=FilterTextBox id=txt" + ColumnNames[i] + " />&nbsp;&nbsp;<Input class=ButtonStyle style=height:20px type=button id=btn" + ColumnNames[i] + " onclick=\"javascript:filtergrid('" + path + "','" + ColumnNames[i] + "');\" value='Go'/>";

x.HeaderText = headerhtml;

if ((_FilterColumnName != null) & (_FilterValue != null))

{

if (ColumnNames[i].Trim().ToUpper() == _FilterColumnName.Trim().ToUpper())

{

//if filterd column then add "Remove" link to the header text.

headerhtml = DisplayNames[i];

headerhtml = headerhtml + " <br> " + "<Input style=width:70px;height:15px type=text class=FilteredTextBox id=txt" + ColumnNames[i] + " value='" + _FilterValue + "' />&nbsp;<Input class=ButtonStyle style=height:20px type=button id=btn" + ColumnNames[i] + " onclick=\"javascript:filtergrid('" + path + "','" + ColumnNames[i] + "');\" value='Go' />";

headerhtml = headerhtml + "&nbsp;&nbsp;" + "<a style=color:Red href=\"javascript:removefilter('" + path + "');\" >Remove</a>";

x.HeaderText = headerhtml;

}

}

}

}

}

x.Visible = true;

//add to datagrid

// ListGrid.DataSource = ListTable;

ListGrid.Columns.Add(x);

}

}

}

}

}

}

protected void ListGrid_PageIndexChanged(object source, DataGridPageChangedEventArgs e)
{
ListGrid.CurrentPageIndex = e.NewPageIndex;
BindData(_path, dtGrid, _ColumnNames, _DisplayColumnNames);
}

}