How to notification show after Form successful submit - html

Question

I change my website template. i change Contact Form also previous contact form work correctly, when i change contact form template than submit form successful notification dont show under submit button. i checked all details but i can not find any error. help me this form.
form code
<form class="contact-form" id="contact-form" method="post" action="sendemail.php">
<div class="form-group tiple">
<input type="text" class="contact-box" name="name" value="" placeholder="Enter Your Name">
</div>
<div class="form-group tiple">
<input type="email" class="contact-box" name="email" value="" placeholder="Enter Your Email">
</div>
<div class="form-group tiple">
<input type="text" pattern="[6|7|8|9][0-9]{9}" class="contact-box" name="phone" value="" placeholder="10 Digit Mobile No.">
</div>
<div class="form-group">
<label>Subject</label>
<select name="subject" class="form-control">
<option value="Demo Registraion">Demo Registraion</option>
<option value="Contact Us">Contact Us</option>
<option value="Feedback">Feedback</option>
<option value="Other">Other</option>
</select>
</div>
<div class="form-group">
<textarea name="message" class="contact-box" placeholder="Your Message" rows="10"></textarea>
</div>
<button type="submit" class="short-line margin-top-10">Submit now</button>
</form>
sendmail.php code
<?php
// Define some constants
define( "RECIPIENT_NAME", "NAME" );
define( "RECIPIENT_EMAIL", "mail#email.com " );
// Read the form values
$success = false;
$senderName = isset( $_POST['name'] ) ? preg_replace( "/[^\.\-\' a-zA-Z0-9]/", "", $_POST['name'] ) : "";
$senderEmail = isset( $_POST['email'] ) ? preg_replace( "/[^\.\-\_\#a-zA-Z0-9]/", "", $_POST['email'] ) : "";
$senderPhone = isset( $_POST['phone'] ) ? preg_replace( "/[6|7|8][0-9][9]/", "", $_POST['phone'] ) : "";
$subject = isset( $_POST['subject'] ) ? preg_replace( "/[^\.\-\' a-zA-Z0-9]/", "", $_POST['subject'] ) : "";
$message = isset( $_POST['message'] ) ? preg_replace( "/(From:|To:|BCC:|CC:|Subject:|Content-Type:)/", "", $_POST['message'] ) : "";
// If all values exist, send the email
if ( $senderName && $senderEmail && $message ) {
$recipient = RECIPIENT_NAME . " <" . RECIPIENT_EMAIL . ">";
$headers = "From: " . $senderName . " <" . $senderEmail . ">";
$mailBody = 'Sender Name: ' . $senderName. "\r\n" . 'Sender Email: ' . $senderEmail . "\r\n" .'Sender Phone: '. $senderPhone . "\r\n" . 'Subject: ' . $subject . "\r\n" . 'Message: ' . $message;
$success = mail( $recipient, $subject, $mailBody, $headers );
echo 'Your Request Send Successful';
echo "<p class='success'>Thanks for contacting us. We will contact you ASAP!</p>";
?>
i want an notification under the submit button
msg submit successfull or failed

Answer 1

You can follow PRG pattern and use RedirectAttributes to add flash attributes.
For example:
#RequestMapping(value = "/contractor", method = RequestMethod.POST)
public String handle(#Valid #ModelAttribute Contractor contractor,
BindingResult result,
RedirectAttributes redirectAttributes) {
// Save contactor ...
redirectAttributes.addFlashAttribute("message", "Successful!");
return "redirect:/someGetUrl";
}
And just show this message in the view rendered by /someGetUrl handler.