Select All Form Fields In A Single Instance With PHP - php

Question

I'm starting to learn PHP and have the code below, which includes a connection to the database from a db.php file, which then runs a query which uses HTML form data that is added to a MYSQL database.
In the code below there is an if statement that means the $firstname field must have content. If I have a larger form and want to ensure every form field is filled in, is there a PHP function where I can select all form fields with a "name" attribute (or something similar)? I appreciate I could write out the if statement x number of times for each field but I was thinking there must be an inbuilt PHP function for this? But I couldn't see anything in the PHP docs?
Any help would be wonderful.
<?php include "db.php"; ?>
<?php
if (isset($_POST['submit'])) {
$firstname = $_POST['first-name'];
$email = $_POST['email'];
if ($firstname == "" || empty($firstname)) {
echo "This field should not be empty";
} else {
$query = "INSERT INTO user(firstname, email) VALUE('{$firstname}', '{$email}')";
$add_name_query = mysqli_query($connection, $query);
if (!$add_name_query) {
die('QUERY FAILED' . mysqli_error($connection));
}
}
}
?>

Answer 1

You could build your own function to make it a little more "dry".
<?php
$firstname = $_POST['first-name'];
$email = $_POST['email'];
$anotherField = "Something";
$andOneMoreField = "Nothing";
function checkInputField($inputField) {
if($inputField == "" || empty($inputField)) {
echo 'This field should not be empty';
return false;
} else {
return true;
}
};
if(
checkInputField($firstname) &&
checkInputField($email) &&
checkInputField($anotherField) &&
checkInputField($andOneMoreField)
// and so on...
) {
echo "Open doors for SQL-Injection";
// db-handling
}
?>
But this is only as food for thought for further learning. This is neither nice code nor a recommendation for implementation.

Answer 2

Another way to do the same:
<?php
function isEmptyField($value) {
return (trim($value) == "" || empty($value)) ? true : false;
}
$fieldNames = array('first-name', 'email'); //You can add others fields name here.
$fieldsOk = true;
foreach($fieldNames as $fieldName) {
if(! array_key_exists($fieldName, $_POST) || isEmptyField($_POST[$fieldName])) {
echo "The field {$fieldName} should not be empty! \r\n";
$fieldsOk = false;
//break; //You could break the validation if a field is empty.
}
}
if($fieldsOk) {
//TODO: INSERT QUERY!
}
?>
But I think you will need others validations for each field according to their data types.