Validate with arrays - php

Question

I'm trying to find a smarter way to validate my inputs with PHP. If the array finds an empty field, it has to add a new element to the array and display an error message.
So far, I haven't succeeded.
The code behind
$felter = array();
if(isset($_POST['submit'])) {
$produktnavn = $_POST['produktnavn'];
$kategori = $_POST['kategori'];
if( !empty( $felter ) ) {
foreach ($felter as $felt) {
if ($felter == '') {
$fejl = true;
}
}
}
else {
$sql = "UPDATE produkt SET produkt_navn = '$produktnavn', fk_kategori_id = '$kategori' WHERE produkt_id=$id";
mysqli_query($db, $sql);
echo "Produktet blev opdateret";
}
Input form
<input type="text" class="form-control" name="produktnavn" value="<?php echo $produktnavn; ?>">

Answer 1

The code starts with $felter = array(); which initializes an empty array.
Then, without changing the array itself, you're checking for non-emptiness of $felter
if( !empty( $felter ) ) {
foreach ($felter as $felt) {
if ($felter == '') {
$fejl = true;
}
}
}
You're trying to iterate over an array that has not gotten any elements pushed into it. And the logic statement if( !empty ($felter)) will also not work as expected either.
As a test, before the check for !empty, put something in the array with $felter[] = 'Test word'; and then, underneath it... (if you're looking for a non-empty array, the logical checker could be if(count($felter)) { before iterating over the array with foreach ($felter as $felt) { if ($felt == '')
$felter = array();
$felter[] = 'Test word';
if(isset($_POST['submit'])) {
$produktnavn = $_POST['produktnavn'];
$kategori = $_POST['kategori'];
if( count( $felter ) ) {
foreach ($felter as $felt) {
if ($felt == '') {
$fejl = true;
}
}
}