如何在同一页面上显示表单错误并保留用户输入的数据？

Question

I have a form that has action="file.php" , That PHP file has the cheeks and outputs , I want these outputs to be on the same form page.

The form exists in an html file :

 <form class="" method="post" action="file.php">
    <!-- Some Form Fields -->
</form>

The file.php contains some checks and outputs like:

if ($_SERVER["REQUEST_METHOD"] == "POST") {
    $name = $_POST['name'];
    if ( empty($name){
        echo "Name can't be empty.";
    }
}

How to show these outputs on the same page next to the form?

Answer 1

If you are posting to the same page, you can echo errors on the same page & retain the posted data no problem with something like this.

in php

   $errors = []
   if (empty($name){
        $errors['name'] = "Name can't be empty.";
    }

... and on the form

<php if (isset($errors['name'])) echo $errors['name']; ?>

<input name='name' value="<?php if (isset($_POST['name'])) echo $_POST['name']; ?>"></input> 

If you are posting to a different url, then you will have to redirect back to the form page or include the form page, and pass the $errors and the $_POST data.