Form Php Validation - php

Question

So i managed to create an ajax form with jquery validation and I need to enchance it with php validation. Here is the code:
<!-- Contact form -->
<div id='contact_form_holder'>
<form action='index.php' method='post' id='contact_form'>
<p>
Your Name:
<div id='name_error' class='error'><img src='images/error.png'> Please enter your Name.</div>
<div><input class="textbox" type='text' name='name' id='name'></div>
</p>
<p>
Your Email:
<div id='email_error' class='error'><img src='images/error.png'> Please enter a valid Email.</div>
<div><input class="textbox" type='text' name='email' id='email'></div>
</p>
<p>
The Subject:
<div id='subject_error' class='error'><img src='images/error.png'> What is the purpose of the contact?</div>
<div><input class="textbox" type='text' name='subject' id='subject'></div>
</p>
<p>
The Message:
<div id='message_error' class='error'><img src='images/error.png'> Forgot why you came here?</div>
<div><textarea class="textbox" name='message' id='message'></textarea></div>
</p>
<div id='mail_success' class='success'><img src='images/success.png'> Your email has been submitted.Thank you.</div>
<div id='mail_fail' class='error'><img src='images/error.png'> There seems to be an internal error.Try later.</div>
<p id='cf_submit_p'>
<input class="button" type='submit' id='send_message' value='Send The Message'>
</p>
</form>
</div>
<!-- /Contact form -->
The send mail php code
$email_to = 'admin#localhost.com'; //the address to which the email will be sent
$name = $_POST['name'];
$email = $_POST['email'];
$subject = $_POST['subject'];
$message = $_POST['message'];
/*the $header variable is for the additional headers in the mail function,
we are asigning 2 values, first one is FROM and the second one is REPLY-TO.
That way when we want to reply the email gmail(or yahoo or hotmail...) will know
who are we replying to. */
$headers = "From: $email\r\n";
$headers .= "Reply-To: $email\r\n";
if(mail($email_to, $subject, $message, $headers)){
echo 'sent'; // we are sending this text to the ajax request telling it that the mail is sent..
}else{
echo 'failed';// ... or this one to tell it that it wasn't sent
}
?>
And the jquery :
/// Contact Form ///
$(document).ready(function(){
$('#send_message').click(function(e){
//stop the form from being submitted
e.preventDefault();
/* declare the variables, var error is the variable that we use on the end
to determine if there was an error or not */
var error = false;
var name = $('#name').val();
var email = $('#email').val();
var subject = $('#subject').val();
var message = $('#message').val();
var re = new RegExp(/^[a-z0-9_\-]+(\.[_a-z0-9\-]+)*#([_a-z0-9\-]+\.)+([a-z]{2}|aero|arpa|biz|com|coop|edu|gov|info|int|jobs|mil|museum|name|nato|net|org|pro|travel)$/);
/* in the next section we do the checking by using VARIABLE.length
where VARIABLE is the variable we are checking (like name, email),
length is a javascript function to get the number of characters.
And as you can see if the num of characters is 0 we set the error
variable to true and show the name_error div with the fadeIn effect.
if it's not 0 then we fadeOut the div( that's if the div is shown and
the error is fixed it fadesOut.
The only difference from these checks is the email checking, we have
email.indexOf('#') which checks if there is # in the email input field.
This javascript function will return -1 if no occurence have been found.*/
if(name.length == 0){
var error = true;
$('#name_error').fadeIn(500);
}else{
$('#name_error').fadeOut(500);
}
if(email.lenght == 0 || !email.match(re)) {
var error = true;
$('#email_error').fadeIn(500);
} else {
$('#email_error').fadeOut(500);
}
if(subject.length == 0){
var error = true;
$('#subject_error').fadeIn(500);
}else{
$('#subject_error').fadeOut(500);
}
if(message.length == 0){
var error = true;
$('#message_error').fadeIn(500);
}else{
$('#message_error').fadeOut(500);
}
//now when the validation is done we check if the error variable is false (no errors)
if(error == false){
//disable the submit button to avoid spamming
//and change the button text to Sending...
$('#send_message').attr({'disabled' : 'true', 'value' : 'Sending...' });
/* using the jquery's post(ajax) function and a lifesaver
function serialize() which gets all the data from the form
we submit it to send_email.php */
$.post("send_email.php", $("#contact_form").serialize(),function(result){
//and after the ajax request ends we check the text returned
if(result == 'sent'){
//if the mail is sent remove the submit paragraph
$('#cf_submit_p').remove();
//and show the mail success div with fadeIn
$('#mail_success').fadeIn(500);
}else{
//show the mail failed div
$('#mail_fail').fadeIn(500);
//reenable the submit button by removing attribute disabled and change the text back to Send The Message
$('#send_message').removeAttr('disabled').attr('value', 'Send The Message');
$(':input','#contact_form')
.not(':button, :submit, :reset, :hidden')
.val('')
.removeAttr('checked')
.removeAttr('selected');
}
});
}
});
});
I have a very poor knowledge of php and I really need someone to help me validate this form with php if javascript is disabled and output the errors inside the correspoding error divs the jquery uses. Help would really be appreciated!

Answer 1

on index.php check values of your html fields
$regex = '/^[_a-z0-9-]+(\.[_a-z0-9-]+)*#[a-z0-9-]+(\.[a-z0-9-]+)*(\.[a-z]{2,3})$/';
if($_REQUEST['name']!="" && $_REQUEST['email']!="" && $_REQUEST['subject'] !="" && $_REQUEST['message']!="")
{
if (preg_match($regex, $_REQUEST['email'])) {
echo $email . \" is a valid email. We can accept it.\";
} else {
echo $email . \" is an invalid email. Please try again.\";
}
}
else{
echo "Error";
}

Answer 2

try to pass an error code to the page with the form via Redirection
http://example.com/form.php?error=1
and check the $_GET["error"] for the error code, display the message that is associated with the error where you want in the page