How do I write data to JSON on RoR?

Question

Ruby on Rails

There is a task to write data either from an input (located outside the form (is it possible to do this without a form at all?)), or from uploaded pictures (you need to get the name + extension from them)
How to implement this on rails? I just started to study, I know that this can be done in php, but I want to learn how to work with rails, and the project has already started to do on it, advise me to read something on the topic of my question, if you drop the necessary links, it will be great in general. Something
like this this is done in php, but you need an analogue on rails

<?
session_start();
  require_once("include/db_connect.php");
?>

<?
if($_SERVER["REQUEST_METHOD"] == "POST"){
  $id=$_SESSION['id'];
  $name_marker=$_POST['name_marker'];
  $description_marker=$_POST['description_marker'];
  $sh=$_POST['sh'];
  $dg=$_POST['dg'];
  $rt=$_POST['rt'];
  
  if(!empty($_SESSION['login_suc'])){
    $sql="INSERT INTO 
    `markers`(`id_marker`, `id_user`, `title`, `desc`, `reit`, `sh`, `dg`) VALUES
     ('','".$id."','".$name_marker."','".$description_marker."','".$rt."','".$sh."','".$dg."')";
      $stmt=$dbh->prepare($sql);
      $stmt->execute();
      echo "Вы добавили маркер";
    $sql="SELECT * FROM markers";
        $query=$dbh->query($sql);
        foreach ($query=$dbh->query($sql) as $row) 
        {
          $array[]=$rows[] = array(
            "name"=>$row["title"],
          "info"=>$row["desc"],
          "reit"=>$row["reit"],
          "lat"=>$row["sh"],
          "lng"=>$row["dg"]
         );
        }
       $file='places.json';
       $a='{"placesData":';
       $a=$a.json_encode($rows).'}';
       file_put_contents($file, $a);
  }else{
    echo "Вам необходимо авторизироваться";
  }
}
?>

Answer 1

To be honest, I hardly understand what exactly is needed, but on a hunch I will suggest reading this rusrails.ru/api-app