php更新查询不会使用pdo更新

Question

I have a edit.php file as seen below. The page shows a blog post via GET['id'] in a form to edit the title and body of that post. When editPostForm is submitted, it should update the database with the new content and redirect back to the /posts/ page. The redirect works, but when viewing the post, nothing has changed about the blog post.

What am I doing wrong?

$post = isset($_GET['id']) ? $_GET['id'] : '';

if (isset($_GET['id']))
{
    $id = $_GET['id'];
    $sql = "SELECT * FROM posts WHERE id = ?";
    $results = $db->prepare($sql);
    $results->bindValue(1, $id);
    $results->execute();
    $post = $results->fetch(PDO::FETCH_ASSOC);
}

if (isset($_POST['editPostForm']))
{
    $title = $_POST["title"];
    $body = $_POST["body"];
    $id = $_GET['id'];

    $stmt = $db->prepare("UPDATE posts SET title = ?, body = ? WHERE id = ?");
    $stmt->bindParam(1, $title);
    $stmt->bindParam(2, $body);
    $stmt->bindParam(3, $id);
    $stmt->execute(); 

    header("Location: posts");
}

$twigContext = array(
    "post" => $post
);

echo $twig->render('edit.html.twig', $twigContext);

HTML File:

  <div class="wrapper">
    <form method="post" action="edit.php" class="editComposeForm">
      <h2>Edit Post</h2>
      <input type="text" value="{{ post.title }}" name="title"><br>
      <textarea name="body">{{ post.body }}</textarea><br>
      <input type="submit" value="Update" name="editPostForm">
    </form>
  </div>

Answer 1

The html form does not have an input with the name id that you are attempting to access in the php code. You can add it either as a hidden form element (first example below) or as part of the query string in the action attribute (second example below).

Add it as a hidden form element:

  <div class="wrapper">
    <form method="post" action="edit.php" class="editComposeForm">

      <input type="hidden" value="{{ post.id }}" name="id">

      <h2>Edit Post</h2>
      <input type="text" value="{{ post.title }}" name="title"><br>
      <textarea name="body">{{ post.body }}</textarea><br>
      <input type="submit" value="Update" name="editPostForm">
    </form>
  </div>

And in the php

$id = $_POST['id'];

OR add it to the query string in the action attribute.

  <div class="wrapper">
    <form method="post" action="edit.php/id={{ post.id }}" class="editComposeForm">
      <h2>Edit Post</h2>
      <input type="text" value="{{ post.title }}" name="title"><br>
      <textarea name="body">{{ post.body }}</textarea><br>
      <input type="submit" value="Update" name="editPostForm">
    </form>
  </div>

And in the php

$id = $_GET['id'];