Check if session data isset and apply error to each item - php

Question

I have to do the following for a large amount of session variables, is there a way I can shorten this code to apply to all the variables rather than repeatedly writing out if(!isset($_SESSION['whatever'])) and adding the apropriate error to the errors array.
if(!isset($_SESSION['fiat'])) {
$errors[fiat] = 'Please enter valid amount';
}
if(!isset($_SESSION['contact'])) {
$errors[contact] = 'Please enter valid contact';
}
if(!isset($_SESSION['name'])) {
$errors[name] = 'Please enter valid name';
}
I have tried some things with for loops and arrays but am really struggling even after some serious googling, so any help much appreciated.
Thanks!
I have now made the following array but am unsure how to use it:
$errors = array(
$_SESSION['fiat'] => 'Please enter valid amount',
$_SESSION['contact'] => 'Please enter valid contact',
$_SESSION['name'] => 'Please enter valid name',
);
Do i do something like the following? Not sure what goes inbetween.
for(!isset($errors)){
}

Answer 1

What you can do is the following:
$errors = array();
// List all session parameters and error messages you want to check here
$valuesToCheck = array(
'fiat' => 'Please enter valid amount',
'contact' => 'Please enter valid contact'
// and so on...
);
// Loop through all values you want to check and validate it. if validation doesn't pass add error message to $errors array.
foreach ($valuesToCheck as $k => $v) {
if(!isset($_SESSION[$k])) {
$errors[$k] = $v;
}
}
// Check if after the validation array with errors is not empty then deal with it.
if (!empty($errors)) {
// Do something with errors here
}
PS: I think you should learn more about software development basics before start writing a code. This will be useful in your further career.