posting a form that has errors then re-displaying that form with errors on page

webdeveloper123 · July 23, 2022

Hi Guys,

I have a simple insert sql form in PDO which inserts the data just fine. Thing is I am now validating the data that goes into the database & this is the first proper time i've done it. At the moment I have only validated First Name field to be between 3-18 characters and that the user must agree to the T's & C's before that form data can be inserted into the database. What happens at the moment If I have less than 3 characters for the first name, when I press submit it goes to a new page, without the form there, but with the error message at the top of the page saying "First name has to be between 3-18 characters. Same kind of thing with T&C, it will take me to a new page without the form there and display error "You have to accept terms" etc

What I want to do is if there are errors on the form, when I press submit, I want the form to re-appear and then be able to put the error messages next to the html element it came from

I know this code isn't great but it's my first proper crack at PDO and validation.

<?php
declare(strict_types = 1);
 ?>

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title> Document </title>
</head>
<body>



<?php

include 'includes/db.php';
//include 'includes/functions.php';

$terms   = '';
$message = '';
$firstName = '';
$messageName = '';

function is_text($text, int $min = 0, int $max = 1000): bool
{
    $length = mb_strlen($text);
    return ($length >= $min and $length <= $max);
}

if ($_SERVER['REQUEST_METHOD'] == 'POST') {

  $sql = "INSERT INTO customer_details (first_name, last_name, address, town, county, post_code, fav_food, birthdate, email, terms) 
          VALUES (:first_name, :last_name, :address, :town, :county, :post_code, :fav_food, :birthdate, :email, :terms);";


$customers['first_name'] = $firstName = $_POST['fname'];
$customers['last_name'] = $lastName = $_POST['lname'];
$customers['address'] = $address = $_POST['address'];
$customers['town'] = $town = $_POST['town'];
$customers['county'] = $county = $_POST['county'];
$customers['post_code'] = $postCode = $_POST['postcode'];
$customers['fav_food'] = $favouriteFood = $_POST['fav_food'];
$customers['birthdate'] = $birthdate = $_POST['birthday'];
$customers['email'] = $email = $_POST['email'];
$customers['terms'] = $terms   = (isset($_POST['terms']) and $_POST['terms'] == true) ? true : false;
$message = $terms ? 'Thank you' : 'You must agree to the terms and conditions';

if ($terms  == false){
    echo $message;
    exit;

}

$valid = is_text($firstName, 3, 18);
    if ($valid) {
        $messageName = '';
    } else {
        $messageName = 'First Name must be 3-18 characters';

    }

    if ($valid == false){
      echo $messageName;
      exit;
    }



$statement = $pdo->prepare($sql);
$statement->execute($customers);




}

?>

<?= $message ?>
  <?= $messageName ?>


<form action="insert.php" method="post">
  <label for="fname">First name:</label><br>
  <input type="text" id="fname" name="fname" value="<?= htmlspecialchars($firstName) ?>"><br>



  
  
  <label for="lname">Last name:</label><br>
  <input type="text" id="lname" name="lname"><br>
  
  <label for="address">Address</label><br>
  <input type="text" id="address" name="address"><br>

  
  <label for="town">Town</label><br>
  <input type="text" id="town" name="town"><br>
  
  <label for="county">County</label><br>
  <input type="text" id="county" name="county"><br>
  
  <label for="postcode">Post Code</label><br>
  <input type="text" id="postcode" name="postcode"><br><br>
  

  <label for="food">What is your favourite food?</label><br>
  <input type="radio" id="burger" name="fav_food" value="Burgers">
  <label for="burger">Burgers</label><br>
  <input type="radio" id="pizza" name="fav_food" value="Pizza">
  <label for="pizza">Pizza</label><br>
  <input type="radio" id="kebab" name="fav_food" value="Kebabs">
  <label for="kebab">Kebabs</label><br><br>
  
  
  <label for="birthday">Birthday:</label>
  <input type="date" id="birthday" name="birthday"><br><br>
  
  <label for="email">Email</label><br>
  <input type="text" id="email" name="email"><br><br>
  
  <input type="checkbox" id="terms" name="terms" value="true" <?= $terms ? 'checked' : '' ?>>
  <label for="terms">I agree to the terms.</label><br><br>

    <input type="submit" value="Submit">  
</form>



</body>
</html>

Thanks

webdeveloper123 · July 23, 2022

I found a few ways such as:

 echo "<meta http-equiv='refresh' content='0'>";

or

header('Location: insert.php');

but none of them show me the error messages related to my validation

ginerjm · July 23, 2022

The trick is to write your form with php variables assigned to the value attibutes of your input tags. When you process the submit button make sure you grab all of the POST values and assign them to these same variables. That way if you have an error you simply resend the same form.

webdeveloper123 · July 23, 2022

But will that make the error show after I have hit submit and the page/form reloads?

webdeveloper123 · July 23, 2022

you mean do something like this?

$customers['first_name'] = $firstName = $_POST['fname'];

  <input type="text" id="fname" name="fname" value="<?= htmlspecialchars($firstName) ?>"><br>

webdeveloper123 · July 23, 2022

hey i think i figured it out

It was the exit command stopping the form/error messages loading :facewall:

Barand · July 23, 2022

Simple example

<?php

if ($_SERVER['REQUEST_METHOD']=='POST')  {
    $errors = [];
    
    $post = array_map('trim', $_POST);
    if ( strlen($post['name']) < 3 || strlen($post['name']) > 18 ) {
        $errors['name'] = 'Must be between 3 and 18 characters';
    }
    if (!isset($post['confirm'])) {
        $errors['confirm'] = 'Box must be checked';
    }
    
    if (!$errors) {
        // update database
        
        header("Refresh: 0");
        exit;
    }
}
?>
<!doctype html>
<html>
<head>
<title>Sample</title>
<style type="text/css">
    .errormsg {
        color : red;    
    }
</style>
</head>
<body>
    <form method='post'>
         Name 
         <input type='text' name='name' value='<?=$_POST['name'] ?? ''?>' >
         <br><span class='errormsg'><?=$errors['name'] ?? ''?></span>
         <br>
         <input type='checkbox' name='confirm' value='1'>
         Click this box
         <br><span class='errormsg'><?=$errors['confirm'] ?? ''?></span>
         <br>
         <input type='submit'>
    </form>
</body>
</html>

webdeveloper123 · July 23, 2022

Hey Barand,

Yes that's pretty much what the new book I got shows how to do it, put the errors into an error array and then at the end see if there are any errors, then go from there. But I got some of the steps mixed up and ended up getting to where I got too.

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posting a form that has errors then re-displaying that form with errors on page

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