Dynamic if-statement with variables? - php

Question

I'm trying to create a dynamic if-statement. The reason I want to do this, is because I need to check server-sided whether inputfields match my regex and are not empty. However, some of my inputfields can be removed in my CMS, meaning there would be more/less inputfields accordingly.
Ideally I would add variables in my if-statement but I'm not 100% sure if that's allowed, so perhaps I would need an other way to solve this problem. Here's what I tried:
if ($f_naw['streetname'] == 1)
{
$streetname= $_POST['streetname']; //Used in INSERT query
$cstreetname = " || $_POST['streetname'] == ''"; //Used to check if field is empty
$pstreetname = " || !preg_match($streetnameReg,$_POST['streetname'])"; //Used to check if it matches my regex
}
else
{
//These variables define variables if inputfields are not shown
$streetname= ''; //No streetname means it's excluded in INSERT query
$cstreetname = ''; //Not needed in check
$pstreetname = ''; //Also not needed in check
}
// more of these if/else statements
if ($_POST['firstname'] == '' || $_POST['lastname'] == '' || $_POST['email'] == '' $cstreetname $cpostalcode $chometown $ctelnr $csex $cdateofbirth)
{
echo 'One of the fields is empty.';
header('refresh:3;url=index.php');
}
else
{
//Regex check, after that more code
}
My idea was to check if a specific field is shown on the front-end and in that case I'm creating some variables that I want to paste in my if-statements.
I'm getting an error saying Server error meaning my php-code would be invalid.
Is it even possible at all to make a dynamic if-statement? If yes, at what part am I failing?
Help is much appreciated! Thanks in advance.

Answer 1

First of all, since it looks like you need to combine all of the conditionals with ||, you can correct your program by writing it like this:
if ($f_naw['streetname'] == 1)
{
$streetname= $_POST['streetname']; //Used in INSERT query
$cstreetname = $_POST['streetname'] == ''; //Used to check if field is empty
$pstreetname = !preg_match($streetnameReg,$_POST['streetname']); //Used to check if it matches my regex
}
else
{
//These variables define variables if inputfields are not shown
$streetname= ''; //No streetname means it's excluded in INSERT query
$cstreetname = false; //Not needed in check
$pstreetname = false; //Also not needed in check
}
if ($_POST['firstname'] == '' || $_POST['lastname'] == '' || $_POST['email'] == '' || $cstreetname || $cpostalcode || $chometown || $ctelnr || $csex || $cdateofbirth)
{
echo 'One of the fields is empty.';
header('refresh:3;url=index.php');
}
This would work, but it's unwieldy. A much better solution would be to use an array (let's name it $errors that gets dynamically populated with errors resulting from validating your fields. Like this:
$errors = array();
if ($f_naw['streetname'] == 1)
{
$streetname= $_POST['streetname']; //Used in INSERT query
if ($streetname == '') {
$errors[] = 'Streetname cannot be empty.'; // message is optional
}
if (!preg_match($streetnameReg,$streetname)) {
$errors[] = 'Streetname is invalid.'; // message is optional
}
}
And then:
if ($errors) {
echo 'There are errors with the data you submitted.';
header('refresh:3;url=index.php');
}
If you provided human-readable error messages you can also arrange for them to be displayed so that the user knows what they need to fix. And of course there are lots of variations of this technique you can use -- e.g. group the error messages by field so that you only show one error for each field.

Answer 2

If you want to check for empty $_POST fields you can do something like this
$error = False;
foreach($_POST as $k => $v)
{
if(empty($v))
{
$error .= "Field " . $k . " is empty\n";
}
}
if(!$error)
{
echo "We don't have any errrors, proceed with code";
}
else
{
echo "Ops we have empty fields.\n";
echo $error;
}
And after you are sure that all the fields are not empty you can do other stuff.