Multiple the same forms and POST method? - php

Question

I have multiple instances of the same form (name / email / message fields) on one page. They all share one class ('.contact-form') and different (dynamically generated IDs).
I validate them using jQuery Tools Validator (it's not relevant though as I have no problems with this at all):
$(".contact-form").validator();
The problem lies in my sendmail.php file I suppose, that's how I get all POST values & validate them:
//grab the fields
$address = trim($_POST['address']);
$title = trim($_POST['title']);
$message = $_POST['message'];
//check if empty
if(empty($name) || empty($title) || empty($message)) {
$wrong = true;
}
if($wrong) {
http_response_code(400);
} else {
// do stuff
http_response_code(200);
}
Now, the issues I'm facing are:
I can't send any other forms excepting the very first on the page, for the rest (even if they're properly filled) I'm getting this error:
Notice: Undefined index: address in mysitesaddress on line 3
after I send the first form - the other forms doesn't act like expected - they are getting through even if all fields are left empty (validator displays errors on front end but then fires "success" after a second because sendmail.php returns "200 OK".
Any ideas how to fix it / check every form instead of just the first one / clear POST data after sending? I'm sure there's an easy way to do that in PHP, I'm not that familiar with that language (mostly a front-end guy) so any help would be much appreciated.
Thank you!
(I've been Googling for an answer for a while now, but looks like "POST" is a tricky name and I'm getting Wordpress/blogs/forums related stuff mostly...)
[update]
Here's the HTML code of each form:
<div class="wrapper">
<form class="contact-form" action="sendmail.php" method="post" novalidate="novalidate">
<input name="title" type="text" required="required" />
<input name="address" type="email" required="required" />
<textarea name="message" required="required" ></textarea>
<input type="Submit" value="Submit" />
</form>
<div class="sucess">
Success message that replaces form ^.
</div>
</div>

Answer 1

The notice implies the 'address' key does not exist.
You should check if the indexes in the $_POST variables are set/exist, e.g. using the PHP isset() function.
This could be caused because you aren't sending the address in every form, just in the first or something like that.
Sample code on how you could use isset to check:
if ( isset($_POST['address']) ) {
//only set $address to the $_POST value if it is set
$address = trim($_POST['address']);
}

Answer 2

I can't see your HTML form code, but I'm guessing your form tag looks like this
<form action="sendmail.php" method="post">
This will take all the fields from the form that was submitted and send them via $_POST to your sendmail.php. After you process the data (edwardmp gave a great tip for making sure the data was there before trying to assign the variables), you would then redirect the page to some type of success landing or back to the original form page. The method I've been using to do this is:
if($wrong) {
$error = "Please check your entry and try again.";
header("Location: http://example.com/formpage.html?error=" . htmlencode($error),true,303);
exit();
} else {
// do stuff
$msg = "Your form was successfully submitted.";
header("Location: http://example.com/formpage.html?msg=" . htmlencode($msg),true,303);
exit();
}
This design makes it so the $_POST data is cleared by reloading the page, and allows you to send messages back to the originating page which you would display through $_GET['msg'], or $_GET['error']. This should stop the forms from submitting erroneously.