PHP form submit and form data validation - php

Question

In PHP is this enough to guarantee a form has been submitted by clicking the form submit button and to verify the content posted is not empty?
if($_SERVER['REQUEST_METHOD']=='POST' && !empty($_POST['field_data']))
{
echo "ok";
}

Answer 1

I think, there may be a way to be sure the form was submitted using your form.
If I would like to do it, I think I will make something like this :
$secure = $_SESSION['form']['submit'] = MD5(time());
<form>
<input type='hidden' name='secure_form' value='<?php echo $secure ?>' />
</form>
And else when submitted check the value :
if($_SERVER['REQUEST_METHOD']=='POST' && isset($_POST['secure_form']) && $_SESSION['form']['submit'] == $_POST['secure_form']) {
//do stuff
}
Of course, you have to add session_start() at the top of the page!

Answer 2

first you need to check $_SERVER['REQUEST_METHOD'] output so best way to convert output in upper
if(strtoupper($_SERVER['REQUEST_METHOD']) === 'POST') {
Then you can check with submit button name also like
<input type="hidden" id="submitted" name="submitted" value="yes"/>
if(strtoupper($_SERVER['REQUEST_METHOD'])=='POST' && isset($_POST['submitted']) && $_POST['submitted'] == 'yes'){
also you can check all values of form which will be submitting by isset() or empty()

Answer 3

I tend to use a hidden form field
<?php
$csrf_token = md5(time().'random string');
$_SESSION['csrf'] = $csrf_token;
?>
<input type="hidden" id="submitted" name="submitted" value="yes"/>
<input type="hidden" id="csrf" name="csrf" value="<?php echo $csrf_token; ?>"/>
Then in my PHP I'd use something like:
if($_SERVER['REQUEST_METHOD']=='POST' && $_POST['submitted'] == 'yes' && $_POST['csrf'] == $_SESSION['csrf']){
// Do something
echo 'Form submitted via POST';
}
Updated to include a CSRF field