Passing on validated variables to a different page (PHP) - php

Question

On form index.php I have three input fields (Name, Surname and Date of Birth) which I want to pass along to form myProfile.php, the user cannot continue to the next myProfile.php unless all three fields have been completed.
How can I send the variables to the next page, once it has been determined that all the input fields are valid? Currently I can determine that all the input fields are valid, but I don't know how to pass the variables along to myProfile.php
Variables and Input handling (index.php):
<?php
$nameErr = $surnameErr = $dobErr = "";
$name = $surname = $dob = "";
if ($_SERVER["REQUEST_METHOD"] == "POST") {
if (empty($_POST["name"])) {
$nameErr = "Name is required";
} else {
$name = test_input($_POST["name"]);
}
if (empty($_POST["surname"])) {
$surnameErr = "Surname is required";
} else {
$surname = test_input($_POST["surname"]);
}
if (empty($_POST["dob"])) {
$dobErr = "Date of Birth is required";
} else {
$dob = test_input($_POST["dob"]);
}
}
function test_input($data) {
$data = trim($data);
$data = stripslashes($data);
$data = htmlspecialchars($data);
return $data;
}
?>
Creating the form (index.php):
<form method="post" action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]);?>">
Name: <input type="text" name="name">
<span class="error">* <?php echo $nameErr;?></span>
<br><br>
Surname:
<input type="text" name="surname">
<span class="error">* <?php echo $surnameErr;?></span>
<br><br>
Date of Birth:
<input type="date" name="dob">
<span class="error">*<?php echo $dobErr;?></span>
<br><br>
<input type="submit" name="submit" value="Submit">
</form>
My problem is that in order to send my name, surname and date of birth to myProfile.php, I need the form action to be action="myProfile.php", however for the input validation to take place it has to be action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]);?>". How can I allow the input validation to take place, and if all the input is valid, then pass the variables along to myProfile.php in order to use the following code:
myProfile.php:
<?php
$name = $_POST['name'];
$surname = $_POST['surname'];
$dob = $_POST['dob'];
echo "<h2>Your Input:</h2>";
echo "My name is " . $name . " " . $surname . ". I am " . date_diff(date_create($dob), date_create('today'))->y . " years old.";
?>

Answer 1

You should be able to use PHP's session functionality to do this. Sessions are not specific to PHP, but PHP has functions which make it easy to maintain data about a specific visitor. This can be tricky because HTTP is a stateless protocol.
In index.php, after you have made sure that the data is valid you can store it in session by calling session_start and using the superglobal $_SESSION variable:
if ($data_is_valid) // you'll have to figure out yourself whether data is valid or not
{
session_start(); // you must call this before using $_SESSION
$_SESSION["valid_data"] = array(
"name" => $name,
"surname" => $surname,
"dob" => $dob
);
// redirect the user to the other page
header("location: myProfile.php");
// always remember to exit after redirecting or code may continue to execute
exit;
}
Then, in my Profile.php, you can call session_start and check for the valid data
session_start();
if (!array_key_exists("valid_data", $_SESSION)) {
die("No valid data found!"); // you might want to redirect back to the first page or something?
}
$data = $_SESSION["valid_data"];
if (!is_array($data)) {
die("Data found is not an array!");
}
// otherwise, data was found...you can keep going!
// you might get errors here if you didn't set these properly on the the previous page
$name = $data['name'];
$surname = $data['surname'];
$dob = $data['dob'];
echo "<h2>Your Input:</h2>";
echo "My name is " . $name . " " . $surname . ". I am " . date_diff(date_create($dob), date_create('today'))->y . " years old.";