How to solve postback in custom sever controls? - asp.net

Question

I am creating custom server controls.I created a textbox in this used this control in my page.But when page is posted back(postback) the value of textbox gets omitted..I thought of using viewstate here but m nt getting textbox value .May be m using in wrong way help me plz
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Linq;
using System.Text;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.HtmlControls;
using System.Reflection;
namespace DNWebComponent {
[DefaultProperty("Text")]
[ToolboxData("<{0}:DNTextBox runat=server></{0}:DNTextBox>")]
public class DNTextBox : WebControl, IDNComponent {
public String _ConnectedField;
private string _label;
private TextBox _txtBox;
private string _connectedField;
private string _MultiSeekField;
private string _InputTable;
public string ControlClientID;
public DNTextBox() {
_txtBox = new TextBox();
}
[PersistToViewState]
[Bindable(true)]
[Category("Appearance")]
[DefaultValue("")]
[Localizable(true)]
public string Text {
get {
String s = (String)ViewState["Text"];
return ((s == null) ? "[" + AspTextBox.Text + "]" : s);
}
set {
ViewState["Text"] = value;
}
}
public DNTextBox(string label)
: this() {
this._label = label;
}
public String Label {
get { return _label; }
set { _label = value; }
}
public String ConnectedField {
get { return _connectedField; }
set { _connectedField = value; }
}
public String MultiSeekField {
get { return _MultiSeekField; }
set { _MultiSeekField = value; }
}
public String InputTable {
get { return _InputTable; }
set { _InputTable = value; }
}
public TextBox AspTextBox {
get { return _txtBox; }
set { _txtBox = value; }
}
public string DivCss { get; set; }
protected override void RenderContents(HtmlTextWriter output) {
output.Write("<div class=\"" + DivCss + "\" >");
output.Write(Text);
output.Write(_label + ": ");
_txtBox.RenderControl(output);
output.Write("</div>");
}
public bool FillControl() {
return false;
}
protected override void LoadViewState(object savedState) {
base.LoadViewState(savedState);
PropertyInfo[] properties = GetType().GetProperties();
foreach (PropertyInfo property in properties) {
object[] attributes = property.GetCustomAttributes(typeof(PersistToViewState), true);
if (attributes.Length > 0) {
if (ViewState[property.Name] != null)
property.SetValue(this, ViewState[property.Name], null);
}
}
}
protected override object SaveViewState() {
ViewState["Text"] = AspTextBox.Text;
//PropertyInfo[] properties = GetType().GetProperties();
//foreach (PropertyInfo property in properties) {
// object[] attributes = property.GetCustomAttributes(typeof(PersistToViewState), true);
// if (attributes.Length > 0)
// ViewState[property.Name] = property.GetValue(this, null);
//}
return base.SaveViewState();
}
[AttributeUsage(AttributeTargets.Property)]
public class PersistToViewState : Attribute {
}
}
}

Answer 1

This is another way to achieve what you are trying to do that will handle all the events and viewstate information:
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Linq;
using System.Text;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.HtmlControls;
using System.Reflection;
namespace DNWebComponent {
[DefaultProperty("Text")]
[ToolboxData("<{0}:DNTextBox runat=server></{0}:DNTextBox>")]
public class DNTextBox : WebControl, IDNComponent {
public String _ConnectedField;
private string _label;
private TextBox _txtBox;
private string _connectedField;
private string _MultiSeekField;
private string _InputTable;
public string ControlClientID;
public DNTextBox() {
_txtBox = new TextBox();
}
[Bindable(true)]
[Category("Appearance")]
[DefaultValue("")]
[Localizable(true)]
public string Text {
get {
String s = (String)ViewState["Text"];
return ((s == null) ? "[" + AspTextBox.Text + "]" : s);
}
set {
ViewState["Text"] = value;
}
}
public DNTextBox(string label)
: this() {
this._label = label;
}
public String Label {
get { return _label; }
set { _label = value; }
}
public String ConnectedField {
get { return _connectedField; }
set { _connectedField = value; }
}
public String MultiSeekField {
get { return _MultiSeekField; }
set { _MultiSeekField = value; }
}
public String InputTable {
get { return _InputTable; }
set { _InputTable = value; }
}
public TextBox AspTextBox {
get { return _txtBox; }
set { _txtBox = value; }
}
public string DivCss { get; set; }
protected override void OnInit(EventArgs e) {
var div = new Panel{ CssClass = DivCss };
div.Controls.Add(new Literal{ Text = Text });
div.Controls.Add(new Literal{ Text = _label + ":" });
div.Controls.Add(_txtBox);
Controls.Add(div);
}
public bool FillControl() {
return false;
}
}
}

Answer 2

This is happening because you have not added the child text box control to your control - because the text-box is not part of control tree, it will not retain its value (or other properties).
You should derive from CompositeControl (or develop UserControl) instead. For example,
...
public class DNTextBox : CompositeControl, IDNComponent {
private TextBox _txtBox;
protected override void CreateChildControls()
{
_txtBox = new TextBox();
_txtBox.ID = "T";
this.Controls.Add(_textBox);
}
public TextBox AspTextBox
{
get { EnsureChildControls(); return _txtBox; }
}
protected override void RenderContents(HtmlTextWriter output)
{
output.Write("<div class=\"" + DivCss + "\" >");
output.Write(Text);
output.Write(_label + ": ");
base.RenderContents(output); // this will create html for child controls
output.Write("</div>");
}
}
Disclaimer: illustrative code, not tested
Whenever, you need to refer to the text-box, make sure that you call EnsureChildControls as shown in AspTextBox property.

Answer 3

This code worked for me.I added a method add attribute
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Linq;
using System.Text;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.HtmlControls;
namespace DNWebComponent {
[DefaultProperty("Text")]
[ToolboxData("<{0}:DNTextBox runat=server></{0}:DNTextBox>")]
public class DNTextBox : TextBox, IDNComponent {
public String _ConnectedField;
private string _label;
private TextBox _txtBox;
private string _connectedField;
private string _MultiSeekField;
private string _InputTable;
public string ControlClientID;
public DNTextBox() {
_txtBox = this;
}
public DNTextBox(string label)
: this() {
this._label = label;
}
public String Label {
get { return _label; }
set { _label = value; }
}
public String ConnectedField {
get { return _connectedField; }
set { _connectedField = value; }
}
public String MultiSeekField {
get { return _MultiSeekField; }
set { _MultiSeekField = value; }
}
public String InputTable {
get { return _InputTable; }
set { _InputTable = value; }
}
public TextBox AspTextBox {
get { return this; }
set { _txtBox = value; }
}
public string DivCss { get; set; }
[System.Security.Permissions.PermissionSet(System.Security.Permissions.SecurityAction.Demand,
Name = "FullTrust")]
protected override void AddAttributesToRender(HtmlTextWriter writer) {
writer.AddAttribute("Label", Label);
writer.AddAttribute("Text", Text);
base.AddAttributesToRender(writer);
}
protected override void RenderContents(HtmlTextWriter output) {
output.Write("<div class=\"" + DivCss + "\" >");
output.Write(_label + ": ");
output.Write("</div>");
}
public bool FillControl() {
return false;
}
}
}