How to use javascript confirm box and alert box in code behind?

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Hello.

I`m making a board using GridView, and I have some problem.

When I try to delete items that check box checked item, I want to like this.

if check box unchecked, and press delete button, alert message "Please check the items"

Or check box checked, and press delete button, confirm message "Check item will deleted!!"

and choose yes selected items are deleted.

How can I make my code? I tried below,

When check box unchecked, alert message shows well, But I try to delete checked items

there`s no confirm message, still confirm message showed.....

Please check my code and give me you advice.

What I have tried:

protected void lnbDel_Click(object sender, EventArgs e)
{
UserBoardDAC dac = new UserBoardDAC();

foreach (GridViewRow gRow in grvList.Rows)
{
CheckBox chk = (CheckBox)gRow.FindControl("chk");
if (chk.Checked)
{
string message = @"
<script type='text/javascript'>
var delConfirm = confirm('Check item will deleted!! Are you sure?');
if (delConfirm)
{
return true;
}
else
{
return false;
}
</script>";
this.ClientScript.RegisterClientScriptBlock(this.GetType(), "script", message);
int boardItemID = Convert.ToInt32(gRow.Cells[0].Text);
dac.DeleteSelectedContents(boardItemID);
}
else
{
string message = @"
<script type='text/javascript'>
alert('Please check the items');
</script>";
this.ClientScript.RegisterClientScriptBlock(this.GetType(), "script", message);
}
}
//PutGridView();
GetCustomPaging(1);

}

Posted 18-Aug-16 23:10pm

RydenChoi

Updated 19-Aug-16 0:56am

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2 solutions

Solution 1

A few possible methods listed here

Asking the user to confirm that they want to continue with an action | The ASP.NET Forums[^]

One thing you have to bear in mind is that when the user clicks the delete button and it goes into your server code, your server code can't execute code on the client so you can't have your server code send javascript to the client, wait for a button to be clicked, then continue on.

Posted 18-Aug-16 23:16pm

F-ES Sitecore

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Vincent Maverick Durano · Accepted Answer · 2016-08-19T00:56:00

Confirmation should be handled at the client-side. Here's a quick example:

Suppose that you have this GridView Columns declaration:

ASP.NET

<columns>
   <asp:templatefield xmlns:asp="#unknown">
   <HeaderTemplate>
      <asp:button id="ButtonDelete" runat="server" text="Delete" />
   </HeaderTemplate>
   <itemtemplate>
      <asp:checkbox id="CheckBox1" runat="server" />
   </itemtemplate>
   </asp:templatefield>
   <asp:boundfield datafield="CustomerID" headertext="ID" readonly="True" xmlns:asp="#unknown" />
   <asp:boundfield datafield="CompanyName" headertext="Company" xmlns:asp="#unknown" />
   <asp:boundfield datafield="ContactName" headertext="Name" xmlns:asp="#unknown" />
   <asp:boundfield datafield="ContactTitle" headertext="Title" xmlns:asp="#unknown" />
   <asp:boundfield datafield="Address" headertext="Address" xmlns:asp="#unknown" />
   <asp:boundfield datafield="Country" headertext="Country" xmlns:asp="#unknown" />
</columns>

You could then write a JavaScript function to handle the confirmation like in the following:

JavaScript

<script type="text/javascript" language="javascript">
        function ConfirmOnDelete(item)
        {
		if(IsValidToDelete()){
          		if (confirm("The following item(s) will be deleted: " + item + "Continue?")==true)
            			return true;
          		else
            		return false;
		}
		else{
			alert("Please check an item.");
		}
        }

	function IsValidToDelete() {
    		var valid = false;
    		var gv = document.getElementById("<%=GridView1.ClientID%>");
    		for (var i = 0; i < gv.getElementsByTagName("input").length; i++) {
        		var node = gv.getElementsByTagName("input")[i];
        		if (node != null && node.type == "checkbox" && node.checked) {
            			valid = true;
            			break;
        		}
    		}

    		return valid;
	}
</script>

Now, you need to hook up a JavaScript onclick event for the Delete button to invoke the ConfirmOnDelete() function. To to do that, you could do it like this at RowDataBound event:

C#

protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
{
        if (e.Row.RowType == DataControlRowType.Header) //check for RowType
        {
            //access the LinkButton from the Header TemplateField using FindControl
            Button b = (Button)e.Row.FindControl("ButtonDelete"); 
            //attach the JavaScript function
            b.Attributes.Add("onclick", "return ConfirmOnDelete();"); 
        }
}

Or the simplest way is to directly call the ConfirmOnDelete() function declaratively like this:

ASP.NET

<asp:button id="ButtonDelete" runat="server" text="Delete" xmlns:asp="#unknown">
	    OnClick="ButtonDelete_Click"
	    OnClientClick="return ConfirmOnDelete();" />
</asp:button>

Notice the call to ConfirmOnDelete() function in OnClientClick event.

For the server-side deletion, I would suggest you to refer this example: GridView Multiple Delete with CheckBox and Confirm[^]