Table of dynamic buttons implemeting IPostBackEventHandler

[Guest]

I'm trying to figure out how to get a table of dynamically created buttons to actually call the command associated with it. It never seems to work, but doing more research it looks like I may need to implement IPostBackEventHandler. However, I cannot find any examples of doing so.

Does anyone have an example of using IPostBackEventHandler/RaisePostBackEvent with an array of controls?

 

[avnrao]

how r u dynamically creating the buttons?
if you are using Button bt = new Button() code in your codebehind file, you
can very well create a delegate and add it to the click event.
you can post your code for us to understand the problem better.

Av.

 

[Guest]

Here's the code

public class GeoEdit : System.Web.UI.Page
{
protected System.Web.UI.WebControls.Table Table1;
protected System.Web.UI.WebControls.Label lblX;
protected System.Web.UI.WebControls.Label lblY;
protected System.Web.UI.WebControls.Label lblBtnClicked;
protected dbTier dbt = new dbTier();
private int curX, curY, gridSize;

private void Page_Load(object sender, System.EventArgs e)
{
if (!IsPostBack)
{
Session["curX"] = 400;
Session["curY"] = 300;
Session["gridSize"] = 11;
drawGeo();
}

}

#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);
}

/// <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

private void btn_Command(object sender, CommandEventArgs e)
{
string[] cellIndex = e.CommandArgument.ToString().Split(new char[] {';'});
lblBtnClicked.Text = "CellClicked";

curX = int.Parse(cellIndex[0]);
curY = int.Parse(cellIndex[1]);

lblX.Text = "Row: " + curX.ToString();
lblY.Text = "Col: " + curY.ToString();

Session["curX"] = curX;
Session["curY"] = curY;

drawGeo();
}

private void drawGeo()
{
curX = (int)Session["curX"];
curY = (int)Session["curY"];
gridSize = (int)Session["gridSize"];

// calculate player location info
int gridShift = gridSize / 2; // ignore remainder
int x1 = curX - gridShift;
int x2 = curX + gridShift;
int y1 = curY - gridShift;
int y2 = curY + gridShift;

lblX.Text = "X: " + curX;
lblY.Text = "Y: " + curY;

// Get Geo info
// DataTable dtGeo = dbt.getGeo(x1, x2, y1, y2);

for (int rowIndex = y1; rowIndex <= y2; rowIndex++)
{
TableRow tr = new TableRow();
Table1.Rows.Add(tr);

for (int colIndex = x1; colIndex <= x2; colIndex++)
{
TableCell tc = new TableCell();
tr.Cells.Add(tc);
Button btn = new Button();
tc.Controls.Add(btn);
btn.CausesValidation = true;
btn.Text = rowIndex.ToString() + ";" + colIndex.ToString();
btn.CommandArgument = rowIndex.ToString() + ";" + colIndex.ToString();
btn.Command += new CommandEventHandler(btn_Command);
}
}

}
}

 

[avnrao]

in your drawGeo method, try this
btn.Click += new System.EventHandler(this.Button1_Click);

instead of
btn.Command += new CommandEventHandler(btn_Command);

Av.

Here's the code

public class GeoEdit : System.Web.UI.Page
{
protected System.Web.UI.WebControls.Table Table1;
protected System.Web.UI.WebControls.Label lblX;
protected System.Web.UI.WebControls.Label lblY;
protected System.Web.UI.WebControls.Label lblBtnClicked;
protected dbTier dbt = new dbTier();
private int curX, curY, gridSize;

private void Page_Load(object sender, System.EventArgs e)
{
if (!IsPostBack)
{
Session["curX"] = 400;
Session["curY"] = 300;
Session["gridSize"] = 11;
drawGeo();
}

}

#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);
}

/// <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

private void btn_Command(object sender, CommandEventArgs e)
{
string[] cellIndex = e.CommandArgument.ToString().Split(new char[] {';'});
lblBtnClicked.Text = "CellClicked";

curX = int.Parse(cellIndex[0]);
curY = int.Parse(cellIndex[1]);

lblX.Text = "Row: " + curX.ToString();
lblY.Text = "Col: " + curY.ToString();

Session["curX"] = curX;
Session["curY"] = curY;

drawGeo();
}

private void drawGeo()
{
curX = (int)Session["curX"];
curY = (int)Session["curY"];
gridSize = (int)Session["gridSize"];

// calculate player location info
int gridShift = gridSize / 2; // ignore remainder
int x1 = curX - gridShift;
int x2 = curX + gridShift;
int y1 = curY - gridShift;
int y2 = curY + gridShift;

lblX.Text = "X: " + curX;
lblY.Text = "Y: " + curY;

// Get Geo info
// DataTable dtGeo = dbt.getGeo(x1, x2, y1, y2);

for (int rowIndex = y1; rowIndex <= y2; rowIndex++)
{
TableRow tr = new TableRow();
Table1.Rows.Add(tr);

for (int colIndex = x1; colIndex <= x2; colIndex++)
{
TableCell tc = new TableCell();
tr.Cells.Add(tc);
Button btn = new Button();
tc.Controls.Add(btn);
btn.CausesValidation = true;
btn.Text = rowIndex.ToString() + ";" + colIndex.ToString();
btn.CommandArgument = rowIndex.ToString() + ";" + colIndex.ToString();
btn.Command += new CommandEventHandler(btn_Command);
}
}

}
}

how r u dynamically creating the buttons?
if you are using Button bt = new Button() code in your codebehind file,
you
can very well create a delegate and add it to the click event.
you can post your code for us to understand the problem better.

Av.

 

[Guest]

I tried that first, didn't change anything. It seems that once the postback occurs, ASP.NET loses the references to the original controls, and cannot fire off the event that was specified without the reference. Why? I dunno. But it's looking like implementing IPostBackEventHandler might be the way to go, but I can't find any idiot's guide to IPostBackEventHandler, the MSDN docs are pretty much worthless to a beginner to the concept.

in your drawGeo method, try this
btn.Click += new System.EventHandler(this.Button1_Click);

instead of
btn.Command += new CommandEventHandler(btn_Command);

Av.

Here's the code

public class GeoEdit : System.Web.UI.Page
{
protected System.Web.UI.WebControls.Table Table1;
protected System.Web.UI.WebControls.Label lblX;
protected System.Web.UI.WebControls.Label lblY;
protected System.Web.UI.WebControls.Label lblBtnClicked;
protected dbTier dbt = new dbTier();
private int curX, curY, gridSize;

private void Page_Load(object sender, System.EventArgs e)
{
if (!IsPostBack)
{
Session["curX"] = 400;
Session["curY"] = 300;
Session["gridSize"] = 11;
drawGeo();
}

}

#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);
}

/// <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

private void btn_Command(object sender, CommandEventArgs e)
{
string[] cellIndex = e.CommandArgument.ToString().Split(new char[] {';'});
lblBtnClicked.Text = "CellClicked";

curX = int.Parse(cellIndex[0]);
curY = int.Parse(cellIndex[1]);

lblX.Text = "Row: " + curX.ToString();
lblY.Text = "Col: " + curY.ToString();

Session["curX"] = curX;
Session["curY"] = curY;

drawGeo();
}

private void drawGeo()
{
curX = (int)Session["curX"];
curY = (int)Session["curY"];
gridSize = (int)Session["gridSize"];

// calculate player location info
int gridShift = gridSize / 2; // ignore remainder
int x1 = curX - gridShift;
int x2 = curX + gridShift;
int y1 = curY - gridShift;
int y2 = curY + gridShift;

lblX.Text = "X: " + curX;
lblY.Text = "Y: " + curY;

// Get Geo info
// DataTable dtGeo = dbt.getGeo(x1, x2, y1, y2);

for (int rowIndex = y1; rowIndex <= y2; rowIndex++)
{
TableRow tr = new TableRow();
Table1.Rows.Add(tr);

for (int colIndex = x1; colIndex <= x2; colIndex++)
{
TableCell tc = new TableCell();
tr.Cells.Add(tc);
Button btn = new Button();
tc.Controls.Add(btn);
btn.CausesValidation = true;
btn.Text = rowIndex.ToString() + ";" + colIndex.ToString();
btn.CommandArgument = rowIndex.ToString() + ";" + colIndex.ToString();
btn.Command += new CommandEventHandler(btn_Command);
}
}

}
}

how r u dynamically creating the buttons?
if you are using Button bt = new Button() code in your codebehind file,
you
can very well create a delegate and add it to the click event.
you can post your code for us to understand the problem better.

Av.

 

[avnrao]

hey..sorry..didnt observe for the first time..
you have to create these controls even in post back also..
put your drawGeo outside IsPostBack.

should work.
Av.

I tried that first, didn't change anything. It seems that once the postback
occurs, ASP.NET loses the references to the original controls, and cannot
fire off the event that was specified without the reference. Why? I dunno.
But it's looking like implementing IPostBackEventHandler might be the way
to go, but I can't find any idiot's guide to IPostBackEventHandler, the
MSDN docs are pretty much worthless to a beginner to the concept.

in your drawGeo method, try this
btn.Click += new System.EventHandler(this.Button1_Click);

instead of
btn.Command += new CommandEventHandler(btn_Command);

Av.

Here's the code

public class GeoEdit : System.Web.UI.Page
{
protected System.Web.UI.WebControls.Table Table1;
protected System.Web.UI.WebControls.Label lblX;
protected System.Web.UI.WebControls.Label lblY;
protected System.Web.UI.WebControls.Label lblBtnClicked;
protected dbTier dbt = new dbTier();
private int curX, curY, gridSize;

private void Page_Load(object sender, System.EventArgs e)
{
if (!IsPostBack)
{
Session["curX"] = 400;
Session["curY"] = 300;
Session["gridSize"] = 11;
drawGeo();
}

}

#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);
}

/// <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

private void btn_Command(object sender, CommandEventArgs e)
{
string[] cellIndex = e.CommandArgument.ToString().Split(new char[]
{';'});
lblBtnClicked.Text = "CellClicked";

curX = int.Parse(cellIndex[0]);
curY = int.Parse(cellIndex[1]);

lblX.Text = "Row: " + curX.ToString();
lblY.Text = "Col: " + curY.ToString();

Session["curX"] = curX;
Session["curY"] = curY;

drawGeo();
}

private void drawGeo()
{
curX = (int)Session["curX"];
curY = (int)Session["curY"];
gridSize = (int)Session["gridSize"];

// calculate player location info
int gridShift = gridSize / 2; // ignore remainder
int x1 = curX - gridShift;
int x2 = curX + gridShift;
int y1 = curY - gridShift;
int y2 = curY + gridShift;

lblX.Text = "X: " + curX;
lblY.Text = "Y: " + curY;

// Get Geo info
// DataTable dtGeo = dbt.getGeo(x1, x2, y1, y2);

for (int rowIndex = y1; rowIndex <= y2; rowIndex++)
{
TableRow tr = new TableRow();
Table1.Rows.Add(tr);

for (int colIndex = x1; colIndex <= x2; colIndex++)
{
TableCell tc = new TableCell();
tr.Cells.Add(tc);
Button btn = new Button();
tc.Controls.Add(btn);
btn.CausesValidation = true;
btn.Text = rowIndex.ToString() + ";" + colIndex.ToString();
btn.CommandArgument = rowIndex.ToString() + ";" + colIndex.ToString();
btn.Command += new CommandEventHandler(btn_Command);
}
}

}
}


:

how r u dynamically creating the buttons?
if you are using Button bt = new Button() code in your codebehind
file,
you
can very well create a delegate and add it to the click event.
you can post your code for us to understand the problem better.

Av.