IPostBackDataHandler not working properly with DataGrid

#11

Yes I have. I had to adapt your code to Visual Studio.NET 2003 though.
It was exhibiting the same problem in that RaisePostDataChangedEvent()
of the user control is not being called even when LoadPostData() of the
user control returns 'true' back to the framework.

Hope you have better luck.

Gaurav Vaish (www.EduJini.IN) wrote:

Quote:

No problem.
Embed the control in DataGrid.... should not be a problem.

Did you try using my control in DataGrid?

--
Happy Hacking,
Gaurav Vaish | http://www.mastergaurav.org
http://www.edujini.in | http://webservices.edujini.in
-------------------

buzlite001 (AT) hotmail (DOT) com> wrote in message
news:1155671651.189969.144180 (AT) m79g2000cwm (DOT) googlegroups.com...
Hello Gaurav,

Thanks for you attempt but it was not answering the initial problem.

The initial problem was that the MyUserControl is embedded in a
Datagrid control. Please checkout the file WebForm1.aspx in my previous
email.

With the configuration as shown in WebForm1.aspx, the user control is
embedded in a datagrid control. When this file is executed and text is
entered into the user control textbox, LoadPostData() of the user
control is invoked. But even though LoadPostData() returns 'true', the
corresponding RaisePostDataChangedEvent() is not called. This is the
problem I am trying to find a solution to.

By the way, I am using Visual Studio.NET 2003 with .NET framework 1.1.
I think you are using Visual Studio.NET 2005 with .NET framework 2.0.
Nevertheless, I do not know if this would affect the result. I would
be curious though.

Thanks

Gaurav Vaish (www.EduJini.IN) wrote:
Problem solved.
btw, the hidden field would be required because of the following reason:

For each ClientID that appears in the form and the control corresponding
to
the same, the IPostBackDataHandler methods would be called.
And for no else.

Here's a trick:

Add a hidden field during 'Render' to the output.

You may download the code (that I wrote) from the following URL:
http://www.edujini.in/samples/ASP.Net/2.0/DataHandlerControl.zip

--
Happy Hacking,
Gaurav Vaish | http://www.mastergaurav.org
http://www.edujini.in | http://webservices.edujini.in
-------------------

"Gaurav Vaish (www.EduJini.IN)" <gaurav.vaish.nospam (AT) nospam (DOT) gmail.com
wrote
in message news:OOulE4BwGHA.1288 (AT) TK2MSFTNGP02 (DOT) phx.gbl...
Let me give it a shot by creating a dummy 'UserControl' on my own.

--
Happy Hacking,
Gaurav Vaish | http://www.mastergaurav.org
http://www.edujini.in | http://webservices.edujini.in
-------------------

buzlite (AT) sympatico (DOT) ca> wrote in message
news:1155591996.737095.53890 (AT) b28g2000cwb (DOT) googlegroups.com...
Hello Gaurav,

I do not know the reasoning for adding a hidden field and what purpose
that would accomplish.

From the sample code attachments, when WebForm1.aspx is run and the
Datagrid generates MyUserControl user control, any text that is
entered
in this user control TextBox would be properly posted back to the
server. This is true in that when MyUserControl.ascx.cs,
LoadPostData() is called, the data can be retrieved from the input
parameter of this method. So...this is working OK.

The problem is, when MyUserControl.ascx.cs, LoadPostData() returns a
value of 'true', RaisePostDataChangedEvent() is never invoked. In the
MyUserControl.ascx.cs code snippet, I hardcoded a return of 'true'.
Even then, RaisePostDataChangedEvent() is never invoked. This is the
main problem that I am experiencing.

Any insights ?

Thanks

Gaurav Vaish (www.EduJini.IN) wrote:
Hi,

The only missing thing that will need to fill, as I think, is a
simple
hidden field... so that it can be captured in LoadPostData.

btw, what happens if you blindly return 'true' in LoadPostData?

--
Happy Hacking,
Gaurav Vaish | http://www.mastergaurav.org
http://www.edujini.in | http://webservices.edujini.in
-------------------

buzlite (AT) sympatico (DOT) ca> wrote in message
news:1155567351.199524.188830 (AT) m79g2000cwm (DOT) googlegroups.com...
Hello All,
Any help would be appreciated.
Thanks

buzlite (AT) sympatico (DOT) ca wrote:
Hello All,

I've posted this in
microsoft.public.dotnet.framework.aspnet.datagridc ontrol but got
not
reply so I'll try my luck here.

Any help would be greatly appreciated.
Thanks

I am having some difficulties with a user control implementing
IPostBackDataHandler when it is placed inside a datagrid.

I have created a user control (MyUserControl.ascx) containing 1
TextBox
that implements the IPostBackDataHandler.
I have also created a form (WebForm1.aspx) that contains 1
datagrid
of
which the datagrid contains the above user control as specified in
its
template.

The purpose is to dynamically create one MyUserControl for each
item
in
the datasource for display and editing.

When the program is run and text is entered into MyUserControl's
textbox, the LoadPostData() of MyUserControl.ascx is called as
expected. But even though LoadPostData() returns true the
corresponding RaisePostDataChangedEvent() is not called.

Note: if I were to simply include the MyUserControl.ascx in
WebForm1.aspx, then both LoadPostData() and
RaisePostDataChangedEvent()
of MyUserControl.ascx are called as expected.

Would someone give me some insight as to why this is not working ?
Am
I missing a step somewhere ?

Attached is the bare essential code snippets to reproduce the
problem.

MyUserControl.ascx
-----------------------------------------------------
%@ Control Language="c#" AutoEventWireup="false"
Codebehind="MyUserControl.ascx.cs" Inherits="test.MyUserControl"
TargetSchema="http://schemas.microsoft.com/intellisense/ie5"%
asp:TextBox id="TextBox1" runat="server"></asp:TextBox

MyUserControl.ascx.cs
-----------------------------------------------------
public class MyUserControl : System.Web.UI.UserControl,
IPostBackDataHandler, INamingContainer
{
protected System.Web.UI.WebControls.TextBox TextBox1;

#region Web Form Designer generated code
override protected void OnInit(EventArgs e)
{
//
// CODEGEN: This call is required by the ASP.NET Web Form
Designer.
//
InitializeComponent();
base.OnInit(e);

if (Page != null)
{
Page.RegisterRequiresPostBack(this);
}
}

/// <summary
/// Required method for Designer support - do not modify
/// the contents of this method with the code editor.
/// </summary
private void InitializeComponent()
{
this.Load += new System.EventHandler(this.Page_Load);

}
#endregion

public virtual bool LoadPostData(string postDataKey,
System.Collections.Specialized.NameValueCollection postCollection)
{
return true;
}

public virtual void RaisePostDataChangedEvent()
{
}

private void Page_Load(object sender, System.EventArgs e)
{
}
}

WebForm1.aspx
------------------------------------------------------
%@ Register TagPrefix="f4c" TagName="MyUserControl"
Src="MyUserControl.ascx" %
%@ Page language="c#" Codebehind="WebForm1.aspx.cs"
AutoEventWireup="false" Inherits="test.WebForm1" %
...
form id="Form1" method="post" runat="server"
asp:datagrid id="dgListing" runat="server"
AutoGenerateColumns="False"
Columns
asp:TemplateColumn
ItemTemplate
f4c:MyUserControl id="MyUserControl1"
runat="server"></f4c:MyUserControl
/ItemTemplate
/asp:TemplateColumn
/Columns
/asp:datagrid
asp:Button id="Button1" runat="server"
Text="Button"></asp:Button
/form

WebForm1.aspx.cs
------------------------------------------------------
public class WebForm1 : System.Web.UI.Page
{

...
private void Page_Load(object sender, System.EventArgs e)
{
//setup handlers
this.Button1.Click += new System.EventHandler(this.Button1_Click);

//setup datagrid
dgListing.DataSource = this.CreateDataSource();
dgListing.DataBind();
}

private void Button1_Click(object sender, System.EventArgs e)
{
}

ICollection CreateDataSource()
{
DataTable dt = new DataTable();
DataRow dr;

dt.Columns.Add(new DataColumn("SomeColumn", typeof(Int32)));

for (int i = 0; i < 2; i++)
{
dr = dt.NewRow();
dr[0] = i;
dt.Rows.Add(dr);
}

DataView dv = new DataView(dt);
return dv;
}
}

#12

hi, the reason your postDataChanged event never makes it is because you have
the user control nested in a datagrid. The datagrid control internally
overrides the onBubbleEvent, and only raises command event, to which you can
get to using the ItemCommand method exposed by the datagrid, giving you a
central location to branch out. Only command events are raised and exposed
via the ItemCommand method because command events can contain CommandName
and CommandArgument properties which can futher be used to distinguish
between who fired what event(stored by you in CommandName property), and
also a chance to pass some custom data(via the commandArgument property) .

In your case you want to fire a non command event, so
1. Nothing will be fired in the DataGrids ItemCommand, and
2. the event is supressed since onbubble event is overridden by the datagrid
and no action is provided to handle any events raised other than command
events.

To work around, you can expose a textchanged event by your usercontrol
class, and attach the event declaratively as the following code snippet,
note OnTextChanged="WebUserControl11_TextChanged".

Another mistake i have seen in your code is that you rebind your datagrid in
page_load, whether its postback or not. If you do this, then the datagrid
will rebind, rebuilding everything and you lose state. This also will
execute before you user control gets a chance to inspect postdata changes.
So only rebind the grid, if its not a postback scenario.

Regards,
Alessandro Zifiglio
http://www.AsyncUI.net

<asp

ataGrid id="DataGrid1" runat="server" EnableViewState="True"
AutoGenerateColumns="False">
<Columns>
<asp:TemplateColumn HeaderText="Template Column1">
<ItemTemplate>
<uc1:WebUserControl1 id="WebUserControl11"
OnTextChanged="WebUserControl11_TextChanged"
runat="server"></uc1:WebUserControl1>
</ItemTemplate>
</asp:TemplateColumn>
</Columns>
</asp

ataGrid>

public void WebUserControl11_TextChanged(object sender, System.EventArgs e)
{
string text1 = (string)((WebUserControl1)sender).Text;
Response.Write(text1);
}

In your user control class you would be doing this to expose the public
event :
----------------------------------------------------------------------------------

public class WebUserControl1 : System.Web.UI.UserControl,
System.Web.UI.IPostBackDataHandler, System.Web.UI.INamingContainer
{
protected System.Web.UI.WebControls.TextBox TextBox1;

public event EventHandler TextChanged;
public string Text
{
get
{
return this.TextBox1.Text;
}

set
{
this.TextBox1.Text = value;
}
}

// return true only if the text has changed
// otherwise false.
public virtual bool LoadPostData(string postDataKey, NameValueCollection
postCollection)
{

String presentValue = Text;
String postedValue = postCollection[postDataKey];
if (postedValue == null)
postedValue = string.Empty;
if (!presentValue.Equals(postedValue))
{
return true;
}
return false;
}

public virtual void RaisePostDataChangedEvent()
{
OnTextChanged(EventArgs.Empty);
}

protected virtual void OnTextChanged(EventArgs e)
{
if (TextChanged != null)
TextChanged(this,e);
}

override protected void OnInit(EventArgs e)
{
InitializeComponent();
base.OnInit(e);

if (Page != null)
{
Page.RegisterRequiresPostBack(this);
}

}

<buzlite (AT) sympatico (DOT) ca> ha scritto nel messaggio
news:1155336658.977686.265490 (AT) p79g2000cwp (DOT) googlegroups.com...

Quote:

Hello All,

I've posted this in
microsoft.public.dotnet.framework.aspnet.datagridc ontrol but got not
reply so I'll try my luck here.

Any help would be greatly appreciated.
Thanks

I am having some difficulties with a user control implementing
IPostBackDataHandler when it is placed inside a datagrid.

I have created a user control (MyUserControl.ascx) containing 1 TextBox
that implements the IPostBackDataHandler.
I have also created a form (WebForm1.aspx) that contains 1 datagrid of
which the datagrid contains the above user control as specified in its
template.

The purpose is to dynamically create one MyUserControl for each item in
the datasource for display and editing.

When the program is run and text is entered into MyUserControl's
textbox, the LoadPostData() of MyUserControl.ascx is called as
expected. But even though LoadPostData() returns true the
corresponding RaisePostDataChangedEvent() is not called.

Note: if I were to simply include the MyUserControl.ascx in
WebForm1.aspx, then both LoadPostData() and RaisePostDataChangedEvent()
of MyUserControl.ascx are called as expected.

Would someone give me some insight as to why this is not working ? Am
I missing a step somewhere ?

Attached is the bare essential code snippets to reproduce the problem.

MyUserControl.ascx
-----------------------------------------------------
%@ Control Language="c#" AutoEventWireup="false"
Codebehind="MyUserControl.ascx.cs" Inherits="test.MyUserControl"
TargetSchema="http://schemas.microsoft.com/intellisense/ie5"%
asp:TextBox id="TextBox1" runat="server"></asp:TextBox

MyUserControl.ascx.cs
-----------------------------------------------------
public class MyUserControl : System.Web.UI.UserControl,
IPostBackDataHandler, INamingContainer
{
protected System.Web.UI.WebControls.TextBox TextBox1;

#region Web Form Designer generated code
override protected void OnInit(EventArgs e)
{
//
// CODEGEN: This call is required by the ASP.NET Web Form Designer.
//
InitializeComponent();
base.OnInit(e);

if (Page != null)
{
Page.RegisterRequiresPostBack(this);
}
}

/// <summary
/// Required method for Designer support - do not modify
/// the contents of this method with the code editor.
/// </summary
private void InitializeComponent()
{
this.Load += new System.EventHandler(this.Page_Load);

}
#endregion

public virtual bool LoadPostData(string postDataKey,
System.Collections.Specialized.NameValueCollection postCollection)
{
return true;
}

public virtual void RaisePostDataChangedEvent()
{
}

private void Page_Load(object sender, System.EventArgs e)
{
}
}

WebForm1.aspx
------------------------------------------------------
%@ Register TagPrefix="f4c" TagName="MyUserControl"
Src="MyUserControl.ascx" %
%@ Page language="c#" Codebehind="WebForm1.aspx.cs"
AutoEventWireup="false" Inherits="test.WebForm1" %
...
form id="Form1" method="post" runat="server"
asp:datagrid id="dgListing" runat="server"
AutoGenerateColumns="False"
Columns
asp:TemplateColumn
ItemTemplate
f4c:MyUserControl id="MyUserControl1"
runat="server"></f4c:MyUserControl
/ItemTemplate
/asp:TemplateColumn
/Columns
/asp:datagrid
asp:Button id="Button1" runat="server" Text="Button"></asp:Button
/form

WebForm1.aspx.cs
------------------------------------------------------
public class WebForm1 : System.Web.UI.Page
{

...
private void Page_Load(object sender, System.EventArgs e)
{
//setup handlers
this.Button1.Click += new System.EventHandler(this.Button1_Click);

//setup datagrid
dgListing.DataSource = this.CreateDataSource();
dgListing.DataBind();
}

private void Button1_Click(object sender, System.EventArgs e)
{
}

ICollection CreateDataSource()
{
DataTable dt = new DataTable();
DataRow dr;

dt.Columns.Add(new DataColumn("SomeColumn", typeof(Int32)));

for (int i = 0; i < 2; i++)
{
dr = dt.NewRow();
dr[0] = i;
dt.Rows.Add(dr);
}

DataView dv = new DataView(dt);
return dv;
}
}

#13

Thanks for the help Alessandro. Your explanation was very insightful.
Your code snippet worked like a charm.

Gaurav, if you're reading this posting, thanks to you too for helping.

Have a great day All.

Alessandro Zifiglio wrote:

Quote:

hi, the reason your postDataChanged event never makes it is because you have
the user control nested in a datagrid. The datagrid control internally
overrides the onBubbleEvent, and only raises command event, to which you can
get to using the ItemCommand method exposed by the datagrid, giving you a
central location to branch out. Only command events are raised and exposed
via the ItemCommand method because command events can contain CommandName
and CommandArgument properties which can futher be used to distinguish
between who fired what event(stored by you in CommandName property), and
also a chance to pass some custom data(via the commandArgument property) .

In your case you want to fire a non command event, so
1. Nothing will be fired in the DataGrids ItemCommand, and
2. the event is supressed since onbubble event is overridden by the datagrid
and no action is provided to handle any events raised other than command
events.

To work around, you can expose a textchanged event by your usercontrol
class, and attach the event declaratively as the following code snippet,
note OnTextChanged="WebUserControl11_TextChanged".

Another mistake i have seen in your code is that you rebind your datagrid in
page_load, whether its postback or not. If you do this, then the datagrid
will rebind, rebuilding everything and you lose state. This also will
execute before you user control gets a chance to inspect postdata changes.
So only rebind the grid, if its not a postback scenario.

Regards,
Alessandro Zifiglio
http://www.AsyncUI.net

asp

ataGrid id="DataGrid1" runat="server" EnableViewState="True"
AutoGenerateColumns="False"
Columns
asp:TemplateColumn HeaderText="Template Column1"
ItemTemplate
uc1:WebUserControl1 id="WebUserControl11"
OnTextChanged="WebUserControl11_TextChanged"
runat="server"></uc1:WebUserControl1
/ItemTemplate
/asp:TemplateColumn
/Columns
/asp

ataGrid

public void WebUserControl11_TextChanged(object sender, System.EventArgs e)
{
string text1 = (string)((WebUserControl1)sender).Text;
Response.Write(text1);
}

In your user control class you would be doing this to expose the public
event :
----------------------------------------------------------------------------------

public class WebUserControl1 : System.Web.UI.UserControl,
System.Web.UI.IPostBackDataHandler, System.Web.UI.INamingContainer
{
protected System.Web.UI.WebControls.TextBox TextBox1;

public event EventHandler TextChanged;
public string Text
{
get
{
return this.TextBox1.Text;
}

set
{
this.TextBox1.Text = value;
}
}

// return true only if the text has changed
// otherwise false.
public virtual bool LoadPostData(string postDataKey, NameValueCollection
postCollection)
{

String presentValue = Text;
String postedValue = postCollection[postDataKey];
if (postedValue == null)
postedValue = string.Empty;
if (!presentValue.Equals(postedValue))
{
return true;
}
return false;
}

public virtual void RaisePostDataChangedEvent()
{
OnTextChanged(EventArgs.Empty);
}

protected virtual void OnTextChanged(EventArgs e)
{
if (TextChanged != null)
TextChanged(this,e);
}

override protected void OnInit(EventArgs e)
{
InitializeComponent();
base.OnInit(e);

if (Page != null)
{
Page.RegisterRequiresPostBack(this);
}

}

buzlite (AT) sympatico (DOT) ca> ha scritto nel messaggio
news:1155336658.977686.265490 (AT) p79g2000cwp (DOT) googlegroups.com...
Hello All,

I've posted this in
microsoft.public.dotnet.framework.aspnet.datagridc ontrol but got not
reply so I'll try my luck here.

Any help would be greatly appreciated.
Thanks

I am having some difficulties with a user control implementing
IPostBackDataHandler when it is placed inside a datagrid.

I have created a user control (MyUserControl.ascx) containing 1 TextBox
that implements the IPostBackDataHandler.
I have also created a form (WebForm1.aspx) that contains 1 datagrid of
which the datagrid contains the above user control as specified in its
template.

The purpose is to dynamically create one MyUserControl for each item in
the datasource for display and editing.

When the program is run and text is entered into MyUserControl's
textbox, the LoadPostData() of MyUserControl.ascx is called as
expected. But even though LoadPostData() returns true the
corresponding RaisePostDataChangedEvent() is not called.

Note: if I were to simply include the MyUserControl.ascx in
WebForm1.aspx, then both LoadPostData() and RaisePostDataChangedEvent()
of MyUserControl.ascx are called as expected.

Would someone give me some insight as to why this is not working ? Am
I missing a step somewhere ?

Attached is the bare essential code snippets to reproduce the problem.

MyUserControl.ascx
-----------------------------------------------------
%@ Control Language="c#" AutoEventWireup="false"
Codebehind="MyUserControl.ascx.cs" Inherits="test.MyUserControl"
TargetSchema="http://schemas.microsoft.com/intellisense/ie5"%
asp:TextBox id="TextBox1" runat="server"></asp:TextBox

MyUserControl.ascx.cs
-----------------------------------------------------
public class MyUserControl : System.Web.UI.UserControl,
IPostBackDataHandler, INamingContainer
{
protected System.Web.UI.WebControls.TextBox TextBox1;

#region Web Form Designer generated code
override protected void OnInit(EventArgs e)
{
//
// CODEGEN: This call is required by the ASP.NET Web Form Designer.
//
InitializeComponent();
base.OnInit(e);

if (Page != null)
{
Page.RegisterRequiresPostBack(this);
}
}

/// <summary
/// Required method for Designer support - do not modify
/// the contents of this method with the code editor.
/// </summary
private void InitializeComponent()
{
this.Load += new System.EventHandler(this.Page_Load);

}
#endregion

public virtual bool LoadPostData(string postDataKey,
System.Collections.Specialized.NameValueCollection postCollection)
{
return true;
}

public virtual void RaisePostDataChangedEvent()
{
}

private void Page_Load(object sender, System.EventArgs e)
{
}
}

WebForm1.aspx
------------------------------------------------------
%@ Register TagPrefix="f4c" TagName="MyUserControl"
Src="MyUserControl.ascx" %
%@ Page language="c#" Codebehind="WebForm1.aspx.cs"
AutoEventWireup="false" Inherits="test.WebForm1" %
...
form id="Form1" method="post" runat="server"
asp:datagrid id="dgListing" runat="server"
AutoGenerateColumns="False"
Columns
asp:TemplateColumn
ItemTemplate
f4c:MyUserControl id="MyUserControl1"
runat="server"></f4c:MyUserControl
/ItemTemplate
/asp:TemplateColumn
/Columns
/asp:datagrid
asp:Button id="Button1" runat="server" Text="Button"></asp:Button
/form

WebForm1.aspx.cs
------------------------------------------------------
public class WebForm1 : System.Web.UI.Page
{

...
private void Page_Load(object sender, System.EventArgs e)
{
//setup handlers
this.Button1.Click += new System.EventHandler(this.Button1_Click);

//setup datagrid
dgListing.DataSource = this.CreateDataSource();
dgListing.DataBind();
}

private void Button1_Click(object sender, System.EventArgs e)
{
}

ICollection CreateDataSource()
{
DataTable dt = new DataTable();
DataRow dr;

dt.Columns.Add(new DataColumn("SomeColumn", typeof(Int32)));

for (int i = 0; i < 2; i++)
{
dr = dt.NewRow();
dr[0] = i;
dt.Rows.Add(dr);
}

DataView dv = new DataView(dt);
return dv;
}
}

#14

your welcome.

Regards,
Alessandro Zifiglio
http://www.AsyncUI.net

<buzlite (AT) sympatico (DOT) ca> ha scritto nel messaggio
news:1155919853.934639.117020 (AT) i3g2000cwc (DOT) googlegroups.com...

Quote:

Thanks for the help Alessandro. Your explanation was very insightful.
Your code snippet worked like a charm.

Gaurav, if you're reading this posting, thanks to you too for helping.

Have a great day All.

Alessandro Zifiglio wrote:
hi, the reason your postDataChanged event never makes it is because you
have
the user control nested in a datagrid. The datagrid control internally
overrides the onBubbleEvent, and only raises command event, to which you
can
get to using the ItemCommand method exposed by the datagrid, giving you a
central location to branch out. Only command events are raised and
exposed
via the ItemCommand method because command events can contain CommandName
and CommandArgument properties which can futher be used to distinguish
between who fired what event(stored by you in CommandName property), and
also a chance to pass some custom data(via the commandArgument property)
.

In your case you want to fire a non command event, so
1. Nothing will be fired in the DataGrids ItemCommand, and
2. the event is supressed since onbubble event is overridden by the
datagrid
and no action is provided to handle any events raised other than command
events.

To work around, you can expose a textchanged event by your usercontrol
class, and attach the event declaratively as the following code snippet,
note OnTextChanged="WebUserControl11_TextChanged".

Another mistake i have seen in your code is that you rebind your datagrid
in
page_load, whether its postback or not. If you do this, then the datagrid
will rebind, rebuilding everything and you lose state. This also will
execute before you user control gets a chance to inspect postdata
changes.
So only rebind the grid, if its not a postback scenario.

Regards,
Alessandro Zifiglio
http://www.AsyncUI.net

asp

ataGrid id="DataGrid1" runat="server" EnableViewState="True"
AutoGenerateColumns="False"
Columns
asp:TemplateColumn HeaderText="Template Column1"
ItemTemplate
uc1:WebUserControl1 id="WebUserControl11"
OnTextChanged="WebUserControl11_TextChanged"
runat="server"></uc1:WebUserControl1
/ItemTemplate
/asp:TemplateColumn
/Columns
/asp

ataGrid

public void WebUserControl11_TextChanged(object sender, System.EventArgs
e)
{
string text1 = (string)((WebUserControl1)sender).Text;
Response.Write(text1);
}

In your user control class you would be doing this to expose the public
event :
----------------------------------------------------------------------------------

public class WebUserControl1 : System.Web.UI.UserControl,
System.Web.UI.IPostBackDataHandler, System.Web.UI.INamingContainer
{
protected System.Web.UI.WebControls.TextBox TextBox1;

public event EventHandler TextChanged;
public string Text
{
get
{
return this.TextBox1.Text;
}

set
{
this.TextBox1.Text = value;
}
}

// return true only if the text has changed
// otherwise false.
public virtual bool LoadPostData(string postDataKey,
NameValueCollection
postCollection)
{

String presentValue = Text;
String postedValue = postCollection[postDataKey];
if (postedValue == null)
postedValue = string.Empty;
if (!presentValue.Equals(postedValue))
{
return true;
}
return false;
}

public virtual void RaisePostDataChangedEvent()
{
OnTextChanged(EventArgs.Empty);
}

protected virtual void OnTextChanged(EventArgs e)
{
if (TextChanged != null)
TextChanged(this,e);
}

override protected void OnInit(EventArgs e)
{
InitializeComponent();
base.OnInit(e);

if (Page != null)
{
Page.RegisterRequiresPostBack(this);
}

}

buzlite (AT) sympatico (DOT) ca> ha scritto nel messaggio
news:1155336658.977686.265490 (AT) p79g2000cwp (DOT) googlegroups.com...
Hello All,

I've posted this in
microsoft.public.dotnet.framework.aspnet.datagridc ontrol but got not
reply so I'll try my luck here.

Any help would be greatly appreciated.
Thanks

I am having some difficulties with a user control implementing
IPostBackDataHandler when it is placed inside a datagrid.

I have created a user control (MyUserControl.ascx) containing 1 TextBox
that implements the IPostBackDataHandler.
I have also created a form (WebForm1.aspx) that contains 1 datagrid of
which the datagrid contains the above user control as specified in its
template.

The purpose is to dynamically create one MyUserControl for each item in
the datasource for display and editing.

When the program is run and text is entered into MyUserControl's
textbox, the LoadPostData() of MyUserControl.ascx is called as
expected. But even though LoadPostData() returns true the
corresponding RaisePostDataChangedEvent() is not called.

Note: if I were to simply include the MyUserControl.ascx in
WebForm1.aspx, then both LoadPostData() and RaisePostDataChangedEvent()
of MyUserControl.ascx are called as expected.

Would someone give me some insight as to why this is not working ? Am
I missing a step somewhere ?

Attached is the bare essential code snippets to reproduce the problem.

MyUserControl.ascx
-----------------------------------------------------
%@ Control Language="c#" AutoEventWireup="false"
Codebehind="MyUserControl.ascx.cs" Inherits="test.MyUserControl"
TargetSchema="http://schemas.microsoft.com/intellisense/ie5"%
asp:TextBox id="TextBox1" runat="server"></asp:TextBox

MyUserControl.ascx.cs
-----------------------------------------------------
public class MyUserControl : System.Web.UI.UserControl,
IPostBackDataHandler, INamingContainer
{
protected System.Web.UI.WebControls.TextBox TextBox1;

#region Web Form Designer generated code
override protected void OnInit(EventArgs e)
{
//
// CODEGEN: This call is required by the ASP.NET Web Form Designer.
//
InitializeComponent();
base.OnInit(e);

if (Page != null)
{
Page.RegisterRequiresPostBack(this);
}
}

/// <summary
/// Required method for Designer support - do not modify
/// the contents of this method with the code editor.
/// </summary
private void InitializeComponent()
{
this.Load += new System.EventHandler(this.Page_Load);

}
#endregion

public virtual bool LoadPostData(string postDataKey,
System.Collections.Specialized.NameValueCollection postCollection)
{
return true;
}

public virtual void RaisePostDataChangedEvent()
{
}

private void Page_Load(object sender, System.EventArgs e)
{
}
}

WebForm1.aspx
------------------------------------------------------
%@ Register TagPrefix="f4c" TagName="MyUserControl"
Src="MyUserControl.ascx" %
%@ Page language="c#" Codebehind="WebForm1.aspx.cs"
AutoEventWireup="false" Inherits="test.WebForm1" %
...
form id="Form1" method="post" runat="server"
asp:datagrid id="dgListing" runat="server"
AutoGenerateColumns="False"
Columns
asp:TemplateColumn
ItemTemplate
f4c:MyUserControl id="MyUserControl1"
runat="server"></f4c:MyUserControl
/ItemTemplate
/asp:TemplateColumn
/Columns
/asp:datagrid
asp:Button id="Button1" runat="server" Text="Button"></asp:Button
/form

WebForm1.aspx.cs
------------------------------------------------------
public class WebForm1 : System.Web.UI.Page
{

...
private void Page_Load(object sender, System.EventArgs e)
{
//setup handlers
this.Button1.Click += new System.EventHandler(this.Button1_Click);

//setup datagrid
dgListing.DataSource = this.CreateDataSource();
dgListing.DataBind();
}

private void Button1_Click(object sender, System.EventArgs e)
{
}

ICollection CreateDataSource()
{
DataTable dt = new DataTable();
DataRow dr;

dt.Columns.Add(new DataColumn("SomeColumn", typeof(Int32)));

for (int i = 0; i < 2; i++)
{
dr = dt.NewRow();
dr[0] = i;
dt.Rows.Add(dr);
}

DataView dv = new DataView(dt);
return dv;
}
}

#15

Quote:

Gaurav, if you're reading this posting, thanks to you too for helping.

Always welcome... :-)

--
Happy Hacking,
Gaurav Vaish | http://www.mastergaurav.org
http://www.edujini.in | http://webservices.edujini.in
-------------------

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IPostBackDataHandler not working properly with DataGrid

ASP.net Building Controls microsoft.public.dotnet.framework.aspnet.buildingcontrols

Re: IPostBackDataHandler not working properly with DataGrid - 08-16-2006 , 01:20 PM

Re: IPostBackDataHandler not working properly with DataGrid - 08-17-2006 , 11:51 AM

Re: IPostBackDataHandler not working properly with DataGrid - 08-18-2006 , 11:50 AM

Re: IPostBackDataHandler not working properly with DataGrid - 08-19-2006 , 04:52 AM

Re: IPostBackDataHandler not working properly with DataGrid - 08-20-2006 , 06:09 AM