OnClick

I am trying to do a validation using onclick. However, it seems there is something problem. Page does not post to a different page once I added Attributes.Add("onclick", ...

Basically, I am trying to validate at least 1 checkbox selected from a DataGrid template column and proceed to post to a different page if validation pass.
<script language="javascript" type="text/javascript">
    function validateAtLeast1Checkbox()
    {
        var objForm = document.forms[0];
        var atLeast1Checked=false;
        
        // only adjacent counters to be enabled for same row
        for (i=0; i<objForm.elements.length; i++)
        {
            // checkbox and not itself
            if (objForm.elements[i].type=="checkbox" &&
                objForm.elements[i].id.indexOf('chkSelection') >= 0)
            {
                if (objForm.elements[i].checked)
                {
                    atLeast1Checked = true;
                    break;
                }
            }
        }
        
        if (!atLeast1Checked)
        {
            alert('No users are selected');
            return false;
        }
    }
    </script>
 
////
 
                <asp:Button ID="btnReset" runat="server" CssClass="button" Text="Reset Password"
                    EnableViewState="False" OnClick="btnReset_Click" PostBackUrl="~/admin/resetBatchPwd.aspx" />
 
////
 
    protected void Page_Load(object sender, EventArgs e)
    {
        this.btnReset.Attributes.Add("onclick", "return validateAtLeast1Checkbox();");
    }
 
///
    protected void btnReset_Click(object sender, EventArgs e)
    {
        // TODO: Validate at least one checked before submit
 
        string accountIDs = GetSelectedAccountID();
        this.hdnAccountIDs.Value = accountIDs;
    }

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ee_guestAsked:
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ventaurConnect With a Mentor Commented:
My apologies. I forgot about the PostBackUrl being set on that button.

Yes, the OnClick code for that button will not execute on that page, because it posts directly to the "~/admin/resetBatchPwd.aspx" page. Your code will have to be moved to the Page_Load event handler of the other page, including the GetSelectedAccountID function.

Be sure you've read up on cross-page posting so you know how to access the controls of the PreviousPage.
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ventaurCommented:
I highly recommend that you use a CustomValidator instead of the current approach. Remove the Attributes.Add("onclick", ...) code from the Page Load event handler and try the following instead.

Also, add a couple of parameters to your JS function to handle the validity check.
<asp:CustomValidator ID="cvAtLeastOneCheckBox" runat="server" Display="None" ClientValidationFunction="validateAtLeast1Checkbox" />
 
----------------
 
<script language="javascript" type="text/javascript">
function validateAtLeast1Checkbox(sender, args)
{
	var objForm = document.forms[0];
	var atLeast1Checked=false;
	
	// only adjacent counters to be enabled for same row
	for (i=0; i<objForm.elements.length; i++)
	{
		// checkbox and not itself
		if (objForm.elements[i].type=="checkbox" &&
			objForm.elements[i].id.indexOf('chkSelection') >= 0)
		{
			if (objForm.elements[i].checked)
			{
				atLeast1Checked = true;
				break;
			}
		}
	}
	
	if (!atLeast1Checked)
	{
		alert('No users are selected');
		args.IsValid = false;
	}
	else
		args.IsValid = true;
}
</script>

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evilrixSenior Software Engineer (Avast)Commented:
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ee_guestAuthor Commented:
But I will still need the onclick event at the server side.

    private string GetSelectedAccountID()
    {
        string accountIDs = "";

        foreach (DataGridItem dgItem in dgSearch.Items)
        {
            CheckBox chkSelection = (CheckBox)dgItem.FindControl("chkSelection");
            if (chkSelection.Checked)
            {
                accountIDs += (dgItem.FindControl("lblAccountID") as Label).Text + ",";
            }
        }

        if (accountIDs != "")
            accountIDs = accountIDs.Remove(accountIDs.Length - 1, 1);

        return accountIDs;
    }

    protected void btnReset_Click(object sender, EventArgs e)
    {
        // TODO: Validate at least one checked before submit
 
        string accountIDs = GetSelectedAccountID();
        this.hdnAccountIDs.Value = accountIDs;
    }

It seems that lblAccountID is not visible when I do a HTML view source from IE. How come? But definitely it is visible at server side.
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ee_guestAuthor Commented:
I tried both using asp:Label and asp:TextBox in my datagrid but hide the column. The elements are not showing in my HTML view source if I hide the column.
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ventaurCommented:
I'm not sure I follow what you mean by trying "both using asp:Label and asp:TextBox". I thought you were validating a column of check boxes. If you hide a column in a grid, it will not show up in the HTML output at all.

You can keep the OnClick for the button, but will need to wrap the code for that event handler in an "if" statement that checks that the page is valid (see below).
protected void btnReset_Click(object sender, EventArgs e)
{
  if (Page.IsValid) {
    string accountIDs = GetSelectedAccountID();
    this.hdnAccountIDs.Value = accountIDs;
  }
}

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ee_guestAuthor Commented:
It seems like the click event is skipped.
It did not go in at all.

    protected void btnReset_Click(object sender, EventArgs e)
    {
        // TODO: Validate at least one checked before submit
 
        if (Page.IsValid)
        {
            Response.Write("EEE");
            Response.End();
            string accountIDs = GetSelectedAccountID();
            this.hdnAccountIDs.Value = accountIDs;
        }
    }

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ee_guestAuthor Commented:
FYI, I have more than 1 submit button and only the custom validation should only be enabled for one button. How to do that?
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ventaurCommented:
If you are using ASP.NET v2.0, then you can set the ValidationGroup property of both the CustomValidator and the Button to the same value; for example, ValidationGroup="UsersGrid".
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ee_guestAuthor Commented:
Excellent!
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