CustomDataGrid Child controls event problem - weird!?! -- asp.net building controls

YunusEmre
12/21/2004 1:50:47 AM

Hi,

I am trying to build a Custom Web Control that extends the DataGrid control
but I am having problems with the events of the child controls. As you can
see in the following code I have four ImageButtons that I am willing to add
to the grid. They will function as page navigators (First, Previous, Next,
Last).

I put this control on an aspx page. Set the properties of the control to
allow paging, give it the image URLs for the page navigation buttons, write
the code to bind data and run. Sth weird happens. The aspx page uses
GridLayout. MyGrid is in the middle of the page. When the application starts
the grid is in place, the data is on the grid but the buttons are not there.
Even if I force them to render by overriding the "render" method they don't
respond. After I click on another button on the page (which has no relation
with the grid) or one the buttons that I forced to render in the overridden
render method, my page navigation buttons appear at the beginning of the
page, at the upper left corner of the page. I click one of those on the
corner or one of those that are rendered by me, it does its stuff and they
disappear again.

I have read many posts on child controls not firing events but I guess this
one is weird.

1) How can I get the buttons running everytime on the page

2) How can I place them just above the grid.

Here is the code for my customwebcontrol

================================================

using System;

using System.Data;

using System.Drawing;

using System.IO;

using System.Web.UI;

using System.Web.UI.WebControls;

using System.ComponentModel;

namespace MyGridPrj

{

[ToolboxData("<{0}:MyGrid runat=server></{0}:MyGrid>"),

ToolboxBitmap(@"D:\MyGrid\MyGrid.bmp")]

public class MyGrid : System.Web.UI.WebControls.DataGrid,
System.Web.UI.INamingContainer

{

protected override void CreateChildControls()

{

this.Controls.Clear();

base.CreateChildControls ();

firstButton = new ImageButton();

firstButton.CommandName = "First";

firstButton.ImageUrl = firstButtonURL;

firstButton.Command += new CommandEventHandler(OnPageButton_Command);

prevButton = new ImageButton();

prevButton.CommandName = "Prev";

prevButton.ImageUrl = prevButtonURL;

prevButton.Command += new CommandEventHandler(OnPageButton_Command);

nextButton = new ImageButton();

nextButton.CommandName = "Next";

nextButton.ImageUrl = nextButtonURL;

nextButton.Command += new CommandEventHandler(OnPageButton_Command);

lastButton = new ImageButton();

lastButton.CommandName = "Last";

lastButton.ImageUrl = lastButtonURL;

lastButton.Command += new CommandEventHandler(this.OnPageButton_Command);

this.Controls.Add(firstButton);

this.Controls.Add(prevButton);

this.Controls.Add(nextButton);

this.Controls.Add(lastButton);

}

// I have declared this dataSourceTable thing because I want to force the
user of the component to bind a dataTable to the grid, so I manually bind it
to the DataSource property of the base DataGrid class and so I can use a
DataView object to sort,filter ans do stuff like that on the grid. But that
is a future concern... First I have to get these buttons running.

private static DataTable dataSourceTable;

public DataTable DataSourceTable{

get

{

return dataSourceTable;

}

set

{

dataSourceTable = value;

this.DataSource = dataSourceTable;

}

}

#region Page Navigation Button Declarations

private ImageButton firstButton;

private string firstButtonURL;

[Bindable(true), Category("Paging"), Description("URL of the image to show
as a first page button")]

public string FirstButtonURL {

get{ return this.firstButtonURL; }

set{ this.firstButtonURL = value; }

}

private ImageButton prevButton;

private string prevButtonURL;

[Bindable(true), Category("Paging"), Description("URL of the image to show
as a previous page button")]

public string PrevButtonURL {

get{ return this.prevButtonURL; }

set{ this.prevButtonURL = value; }

}

private ImageButton nextButton;

private string nextButtonURL;

[Bindable(true), Category("Paging"), Description("URL of the image to show
as a next page button")]

public string NextButtonURL {

get{ return this.nextButtonURL; }

set{ this.nextButtonURL = value; }

}

private ImageButton lastButton;

private string lastButtonURL;

[Bindable(true), Category("Paging"), Description("URL of the image to show
as a last page button")]

public string LastButtonURL {

get{ return this.lastButtonURL; }

set{ this.lastButtonURL = value; }

}

#endregion

protected void OnPageButton_Command(object source,
System.Web.UI.WebControls.CommandEventArgs e)

{

switch (e.CommandName) {

case "First" : { this.CurrentPageIndex = 0;

break;}

case "Prev" : { if (this.CurrentPageIndex>0) this.CurrentPageIndex =
this.CurrentPageIndex-1;

break;}

case "Next" : { if (this.CurrentPageIndex<this.PageCount-1)
this.CurrentPageIndex = this.CurrentPageIndex+1;

break;}

case "Last" : { this.CurrentPageIndex = this.PageCount-1;

break;}

}

DataSource = dataSourceTable;

DataBind();

}

}

================================================

Elmer Carías
12/21/2004 9:22:51 AM

try with that

public override void DataBind()

{

base.DataBind();

firstButton = new ImageButton();

firstButton.CommandName = "First";

firstButton.ImageUrl = firstButtonURL;

firstButton.Command += new CommandEventHandler(OnPageButton_Command);

prevButton = new ImageButton();

prevButton.CommandName = "Prev";

prevButton.ImageUrl = prevButtonURL;

prevButton.Command += new CommandEventHandler(OnPageButton_Command);

nextButton = new ImageButton();

nextButton.CommandName = "Next";

nextButton.ImageUrl = nextButtonURL;

nextButton.Command += new CommandEventHandler(OnPageButton_Command);

lastButton = new ImageButton();

lastButton.CommandName = "Last";

lastButton.ImageUrl = lastButtonURL;

lastButton.Command += new CommandEventHandler(this.OnPageButton_Command);

this.Controls.Add(firstButton);

this.Controls.Add(prevButton);

this.Controls.Add(nextButton);

this.Controls.Add(lastButton);

}

Delete the method CreateChildControls and use DataBind, i hope that can
helps you

Atte. Elmer Carías
El Salvador, CA
elmer_carias@hotmail.com

[quoted text, click to view]

YunusEmre
12/21/2004 3:57:59 PM

after some more work on the code I came to realize that the call to the
DataBind() method causes the controls collection of the grid to be cleared.
And controls that I put there are also gone. If they are to be cleared
everytime DataBind() is called, how can I add any other controls that I need
on the control?

[quoted text, click to view]

YunusEmre
12/22/2004 3:39:56 PM

yes overriding the DataBind really worked. Thanks a lot

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asp.net building controls : CustomDataGrid Child controls event problem - weird!?!