Bir kısım açıklama yapmış idim fakat sayfayı yenileyince silindi. Direk sayfa yapısına uygun örnek ile aşağıya ekliyorum.
1) Ajax Post Yöntemi ile.
<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.2.1/css/bootstrap.min.css" integrity="sha384-GJzZqFGwb1QTTN6wy59ffF1BuGJpLSa9DkKMp0DgiMDm4iYMj70gZWKYbI706tWS" crossorigin="anonymous">
<title>Hello, world!</title>
</head>
<body>
<button type="button" id="duzenle" class="btn btn-primary btn-sm" data-id="1" data-toggle="modal" data-target="#myModal">Düzenle</button>
<div id="myModal" class="modal fade" role="dialog">
<div class="modal-dialog">
<!-- Modal içeriği-->
<div class="modal-content">
<div class="modal-header">
<button type="button" class="close" data-dismiss="modal">×</button>
<h4 class="modal-title">Modal Başlığı</h4>
</div>
<div class="modal-body">
</div>
<div class="modal-footer">
<button type="button" class="btn btn-default" data-dismiss="modal">Kapat</button>
</div>
</div>
</div>
</div>
<!-- Optional JavaScript -->
<!-- jQuery first, then Popper.js, then Bootstrap JS -->
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.4/jquery.min.js"></script>
<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.2.1/js/bootstrap.min.js" integrity="sha384-B0UglyR+jN6CkvvICOB2joaf5I4l3gm9GU6Hc1og6Ls7i6U/mkkaduKaBhlAXv9k" crossorigin="anonymous"></script>
<script>
$("#duzenle").click(function(e) {
var id= $(this).attr("data-id");
$.ajax({
type: "POST",
url: "post.php",
data: {
id: id,
},
success: function(result) {
$('.modal-body').html(result);
},
});
});
</script>
</body>
</html><?php
$deger = $_POST['id'];
echo $deger;
?>
2 ) Ajax Post Etmeden
<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.2.1/css/bootstrap.min.css" integrity="sha384-GJzZqFGwb1QTTN6wy59ffF1BuGJpLSa9DkKMp0DgiMDm4iYMj70gZWKYbI706tWS" crossorigin="anonymous">
<title>Hello, world!</title>
</head>
<body>
<button type="button" id="duzenle" class="btn btn-primary btn-sm" data-id="1" data-toggle="modal" data-target="#myModal">Düzenle</button>
<div id="myModal" class="modal fade" role="dialog">
<div class="modal-dialog">
<!-- Modal içeriği-->
<div class="modal-content">
<div class="modal-header">
<button type="button" class="close" data-dismiss="modal">×</button>
<h4 class="modal-title">Modal Başlığı</h4>
</div>
<div class="modal-body">
</div>
<div class="modal-footer">
<button type="button" class="btn btn-default" data-dismiss="modal">Kapat</button>
</div>
</div>
</div>
</div>
<!-- Optional JavaScript -->
<!-- jQuery first, then Popper.js, then Bootstrap JS -->
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.4/jquery.min.js"></script>
<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.2.1/js/bootstrap.min.js" integrity="sha384-B0UglyR+jN6CkvvICOB2joaf5I4l3gm9GU6Hc1og6Ls7i6U/mkkaduKaBhlAXv9k" crossorigin="anonymous"></script>
<script>
$(document).on('click', '#duzenle', function() {
var id = $(this).attr("data-id");
$('.modal-body').html(id);
});
</script>
</body>
</html>Anlamadığınız yer olursa sorabilirsiniz.