Stopping empty form submission PHP

Question

I have been trying to implement server validation to prevent blank emails in my contact us page, but I am not sure on how to do it in PHP, here is my code:

Answer 1

You can use filter for this; since you're using the passed email address as part of the mail() operation, it's best to also validate:

$fields = filter_input_array(INPUT_POST, array(
    'name' => FILTER_UNSAFE_RAW,
    'email' => FILTER_VALIDATE_EMAIL,
    'tel' => FILTER_UNSAFE_RAW,
    'message' => FILTER_UNSAFE_RAW,
));

// check for missing fields
if (null === $fields || in_array(null, $fields, true)) {
  // some or all fields missing
} elseif (in_array(false, $fields, true)) {
  // some or all fields failed validation
} else {
  // all fields passed validation
  // use $fields['email'] as the email address
}

I've used FILTER_UNSAFE_RAW for all fields except email, but perhaps there are better filters that apply.