Custom validator fires but does not prevent postback - c#-4.0

Question

I've seen a lot of questions about this already, but I'm stumped! Please help!
I have a customvalidator. It's firing but it's not preventing postback. Please help me in doing so! I can see that console.log registers before the post. But, it posts back anyway. How do I prevent the postback?
I've tried adding a control to validate, and validate empty text equal to true. I also tried adding e.preventdefault, which did not work :(
How can I prevent the postback?
<script type="text/javascript">
//<![CDATA[
function validateWhyUnlikely(source, args) {
console.log(1);
args.isValid = false;
}
//]]>
<asp:TextBox ID="txtWhyUnlikely" runat="server" Rows="4" cols="20"
CssClass="surveyTextArea" />
<asp:CustomValidator runat="server" ID="cfvWhyUnlikley" ErrorMessage="Please provide a reason since you rated an item as unlikely to provide."
CssClass="surveyError surveySmallIndent" Display="Dynamic"
ClientValidationFunction="validateWhyUnlikely" />
<asp:Button ID="btnSubmit" runat="server" Text="Submit" CssClass="smallSpecial" OnClick="btnSubmit_Click" />
jQuery(document).ready(function () {
jQuery('#<%= btnSubmit.ClientID %>').click(function (e) {
if (Page.IsValid == false) {
console.log(false);
e.preventDefault();
return false;
}
});
});

Answer 1

Everything looks ok althought I am not sure why you are attaching the Click function to your submit button. I would remove that and test it as it maybe be overriding the default behavior.
Also I think you need to capitalize the IsValid property:
args.IsValid = false;

Answer 2

I too faced this issue, I was trying to add a custom validator to a dropdownlist which had a selectedIndexChange event attached to it. After i gave incorrect value for dropdown, i was able to se ethe error message i gave in Custom Validator but immediately after it Postback was happening.
However on adding this property CausesValidation="true" to the dropdownlist control resolved my issue.
Postback wasn't happening on incorrect value after adding this property to my dropdown.

Answer 3

If it helps other people, I had a Validation group that I forgot to add the button to.
Make sure to add the button, the textbox and the validator to the same validation group for the postback to be prevented.

Answer 4

I experienced this problem as well.
What I did was, in the C# procedure that was called by the button, at the top I added
if (IsValid == false)
return;
I could not stop it performing the postback so this seemed to me like the only solution.

Answer 5

You are misssing ControlToValidate="txtWhyUnlikely"

Answer 6

Posting this as it might help someone that is getting the same weird behavior.
Initially I had the same issue as this post title. I checked all the suggestions here but my code seemed to be fine.
To fix this I replaced my cause validation control <asp:Button.. with a <button.. . Not sure why this is happening but happy it's working now.
hth

Answer 7

<button tags are missing the correct javascript code to validate.
<asp:Button does have the correct javascript rendered.
I've added this to any button tags:
btn.Attributes("onclick") = StringFmt("if(!Page_ClientValidate(''))return false;")
and that solved the post-back issue. No post-back occurs if the client-side detects an issue.

Answer 8

I solved this problem by creating a variable:
Boolean fieldIsValid = true;
and at the custom validating expression I would change the value if arguments weren't true:
if(args.IsValid == false)
{
fieldIsValid = false;
}
else
{
fieldIsValid = true;
}
Then, I also put that in the submit click method:
protected void submit_Click(object sender, EventArgs e)
{
if (fieldIsValid)
{
//submit my things
}
}