Command event doesn't fire dynamically created buttons.

[spt]

I have ajaxified RadGrid.

In one of the columns I am dynamically creating ImageButtons, like here:

 

 

protected void  RadGrid1_ItemDataBound(object sender, GridItemEventArgs e)
{
    if (e.Item is GridDataItem)
    {
        DataRowView v = (DataRowView)e.Item.DataItem;
        ImageButton lnk = new ImageButton();
        lnk.ImageUrl = "~/Images/view.gif";
        lnk.ToolTip = GetString("TimeSheet");
        lnk.CommandArgument = "test";
        lnk.CommandName = "Redirect";
        lnk.Command += new CommandEventHandler(lnk_Command);
        GridDataItem tem = e.Item as GridDataItem;
        Item["Column"].Controls.AddAt(0, lnk);
 }
}

protected void lnk_Command(object sender, CommandEventArgs e)
{
Session["Redirect"] = e.CommandArgument;
Response.Redirect("Timesheet.aspx");
}

 

 

 

 

When page is loaded first time ImageButton is successfully created and displayed in each row,
but clicking on it doesn't fire lnk_Command event  (I have checked this adding breakpoints in lnk_Command),
Instead of redirecting I get the same page without ImageButtons displayed.
Please advice.

 

 

[Shinu]

Hi,

A better approach is adding control in ItemCreated event than ItemDataBound.

aspx:

    <telerik:GridTemplateColumn UniqueName="Column">
        <ItemTemplate>
        </ItemTemplate>
    </telerik:GridTemplateColumn>

c#:

    protected void RadGrid1_ItemCreated(object sender, GridItemEventArgs e)
    {
        if (e.Item is GridDataItem)
        {
            GridDataItem Item = (GridDataItem)e.Item;
            ImageButton lnk = new ImageButton();
            lnk.ImageUrl = "~/Images/img1.gif";
            lnk.CommandArgument = "test";
            lnk.CommandName = "Redirect";
            Item["Column"].Controls.Add(lnk);
        }
    }

The documentation describes the differences between ItemCreated and ItemDataBound.
Distinguishing the major differences between ItemCreated and ItemDataBound events

-Shinu.

[Daniel]

Hello Igor,

Please examine the following thread:
Solution: Dynamic Link buttons created using ItemCreated not firing ItemCommand

Regards,
Daniel
the Telerik team

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[spt]

Unfortunatelly that doesn't help.
I forgot to explain that I create button in GridGroupHeader row, not in simple DataItem

protected void  RadGrid1_ItemCreated(object sender, GridItemEventArgs e)
{
    if (e.Item is GridGroupHeaderItem)
    {
        DataRowView v = (DataRowView)e.Item.DataItem;
        ImageButton lnk = new ImageButton();
        lnk.ImageUrl = "~/Images/view.gif";
        lnk.ToolTip = GetString("TimeSheet");
        lnk.CommandArgument = "test";
        lnk.CommandName = "Redirect";
        lnk.Command += new CommandEventHandler(lnk_Command);
        GridDataItem tem = e.Item as GridDataItem;
        Item["Column"].Controls.AddAt(0, lnk);
 }
}

protected void lnk_Command(object sender, CommandEventArgs e)
{
Session["Redirect"] = e.CommandArgument;
Response.Redirect("Timesheet.aspx");
}

[Adam Heeg]

The event wont fire until after the page is posted back.  You have to specify a unique ID for your button when you create, and you have to recreate it in the OnInit event.  The OnInit event will then be able to create the controls before the page loads the viewstate.  This means the controls exist allowing viewstate to put the correct data and fire the click event after the pageload event.

So, your buttons are not firing because they no longer exist after the controls are reloaded. 

[spt]

Can you provide a simple example?

[Adam Heeg]

Sorry, I don't have the time to post code for you.  It isn't too hard, just google something like 'maintaining state in dynamic controls in asp.net' or something.  There are lots of examples and explainations available.  You will also need to get a handle on the order of events and what they do in asp.net.  There are very nice and simple flow charts available online for that as well.

Good luck

[Daniel]

Hello Igor,

Please download the attached sample project. It is based on the forum thread I posted below.

protected void RadGrid1_ItemCreated(object sender, GridItemEventArgs e)
{
    if (e.Item is GridGroupHeaderItem)
    {
        GridGroupHeaderItem item = e.Item as GridGroupHeaderItem;
        ImageButton lnk = new ImageButton();
        lnk.ID = "myBtn" + e.Item.ItemIndex;
        lnk.CommandName = "Redirect";
        lnk.Command += new CommandEventHandler(lnk_Command);

        item.DataCell.Controls.Add(lnk);
    }
}

void lnk_Command(object sender, CommandEventArgs e)
{
    RadAjaxPanel1.Alert("Command name: " + e.CommandName);
}

protected void RadGrid1_ItemDataBound(object sender, GridItemEventArgs e)
{
    if (e.Item is GridGroupHeaderItem)
    {
        GridGroupHeaderItem item = e.Item as GridGroupHeaderItem;
        ImageButton lnk = new ImageButton();
        lnk.ID = "myBtn" + e.Item.ItemIndex;
        item.DataCell.Controls.Add(lnk);

        lnk.ImageUrl = "~/btn.png";
        lnk.CommandName = "Redirect";
        lnk.Command += new CommandEventHandler(lnk_Command);
    }
}

Let me know if you need further assistance.

Regards,
Daniel
the Telerik team

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[spt]

Thanks for example,  it works.
But I have the following problem now.
I want to pass a parameter with data from the GridGroupHeader row.
So I planned to have a code something like this:

<GroupByExpressions>
    <telerik:GridGroupByExpression >
        <SelectFields >
            <telerik:GridGroupByField  FieldName="StartDate" HeaderText=" " HeaderValueSeparator="" FormatString="{0:D}" />
        </SelectFields>
        <GroupByFields>
            <telerik:GridGroupByField  FieldName="StartDate"  SortOrder="Ascending" />
        </GroupByFields>
    </telerik:GridGroupByExpression>
</GroupByExpressions>

..............

 if (e.Item is GridGroupHeaderItem)
    {
        GridGroupHeaderItem item = e.Item as GridGroupHeaderItem;
        ImageButton lnk = new ImageButton();
        lnk.ID = "myBtn" + e.Item.ItemIndex;
        lnk.CommandName = "Redirect";

        DataRowView v = (DataRowView)e.Item.DataItem;
        DateTime groupDate = Convert.ToDateTime(v["StartDate"]);
        lnk.CommandArgument = groupDate.ToString("d");


        lnk.Command += new CommandEventHandler(lnk_Command);

        item.DataCell.Controls.Add(lnk);
    }

 
This works in ItemDataBound event, but in ItemCreated I get an exception in the following string:
 

 

 

 

DateTime groupDate = Convert.ToDateTime(v["StartDate"]);

So, I cannot specify a CommandArgument for Button. Please advice.

[Daniel]

Hello Igor,

You should create the control on ItemCreated and then populate it on ItemDataBound.
Please find the modified version of my previous sample project, attached to this post.

Best regards,
Daniel
the Telerik team

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[spt]

Thank you it works as I want now.

Btw,  I also tried

protected void RadGrid1_ItemDataBound(object sender, GridItemEventArgs e)

{

if (e.Item is GridGroupHeaderItem)

{

GridGroupHeaderItem item = e.Item as GridGroupHeaderItem;

ImageButton lnk = new ImageButton();

lnk.ID = "myBtn" + e.Item.ItemIndex;

lnk.ImageUrl = "~/btn.png";

lnk.CommandName = "Redirect";

lnk.CommandArgument = DataBinder.Eval(e.Item.DataItem, "CategoryName").ToString();

lnk.Command += new CommandEventHandler(lnk_Command);

item.DataCell.Controls.Add(lnk);

}

}

instead of your     protected void RadGrid1_ItemDataBound(object sender, GridItemEventArgs e) { if (e.Item is GridGroupHeaderItem) { GridGroupHeaderItem item = e.Item as GridGroupHeaderItem; ImageButton lnk = new ImageButton(); lnk.ID = "myBtn" + e.Item.ItemIndex; item.DataCell.Controls.Add(lnk); lnk.ImageUrl = "~/btn.png"; lnk.CommandName = "Redirect"; lnk.CommandArgument = DataBinder.Eval(e.Item.DataItem, "CategoryName").ToString(); lnk.Command += new CommandEventHandler(lnk_Command); } }  and CommanArgumant was not passed. Can you explain thios behaviour?