Question 271755 in PHP Question posted in
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upload file directly from html-form to mariadb table, in a LONGBLOB column, with php

I try to upload a file from html-form in my mariadb database booksummerytable. I get an db entry in the table, in columns student_id and a book_id, but the file-entry just do not want pass in the LONGBLOB column for the file.

  <?php
  session_start();
  if ($_SESSION["rolle"] === "schueler" && isset($_GET['id'])) {
      $buchId = $_GET['id'];

      $dbHost = '...';
      $dbUser = '...';
      $dbPass = '...';
      $dbName = '...';

      $conn = new mysqli($dbHost, $dbUser, $dbPass, $dbName);

      if ($conn->connect_error) {
          die("Verbindung zur Datenbank fehlgeschlagen: " . $conn->connect_error);
      }

      // Wiederholen Sie Ihre Datenbankabfrage, um die Buchinformationen zu erhalten
      $sql = "SELECT title FROM buecher WHERE id = ?";
      $stmt = $conn->prepare($sql);
      $stmt->bind_param("i", $buchId);
      $stmt->execute();
      $result = $stmt->get_result();

      if ($result->num_rows == 1) {
          $row = $result->fetch_assoc();
          $buchtitel = $row['title'];

          // Hier fügen wir das Formular zum Hochladen der Zusammenfassung hinzu
          echo '<h2>Zusammenfassung für das Buch: ' . $buchtitel . '</h2>';
          echo '<form action="upload_zusammenfassung.php" method="post" enctype="multipart/form-data">';
          echo '    <input type="file" name="zusammenfassung" id="zusammenfassung">';
          echo '    <input type="hidden" name="buch_id" value="' . $buchId . '">';
          echo '    <input type="submit" value="Zusammenfassung hochladen">';
          echo '</form>';
      } else {
          echo "Buch nicht gefunden.";
      }

      $stmt->close();
  }
  ?>

Anothe file, where happen the db-entry

<?php
error_reporting(E_ALL);

session_start();

if ($_SESSION["rolle"] === "schueler" && isset($_FILES['zusammenfassung']) && isset($_POST['buch_id'])) {
    // Verbindung zur Datenbank herstellen
    $dbHost = '...';
    $dbUser = '...';
    $dbPass = '...';
    $dbName = '...';

    $conn = new mysqli($dbHost, $dbUser, $dbPass, $dbName);

    if ($conn->connect_error) {
        die("Verbindung zur Datenbank fehlgeschlagen: " . $conn->connect_error);
    }

    $buchId = $_POST['buch_id'];

    // Dateiinformationen

    $dateiTmpName = $_FILES['zusammenfassung']['tmp_name'];
    $dateiDaten = file_get_contents($dateiTmpName);

    // Schüler-ID aus der Datenbank anhand des Benutzernamens holen
    $schuelerBenutzername = $_SESSION["username"];


    $sqlSchuelerId = "SELECT id_student FROM students WHERE newUsername = ?";
    $stmtSchuelerId = $conn->prepare($sqlSchuelerId);
    $stmtSchuelerId->bind_param("s", $schuelerBenutzername);
    $stmtSchuelerId->execute();
    $stmtSchuelerId->bind_result($schuelerId);
    $stmtSchuelerId->fetch();
    $stmtSchuelerId->close();


        // SQL-Befehl, um die Zusammenfassung in der Datenbank zu speichern
        $sql = "INSERT INTO buchzusammenfassung (idSchueler, idBuch, datei) VALUES (?, ?, ?)";
        $stmt = $conn->prepare($sql);
        $stmt->bind_param("iib", $schuelerId, $buchId, $dateiDaten);

        if ($stmt->execute()) {
            echo "Die Zusammenfassung wurde erfolgreich hochgeladen und in der Datenbank gespeichert.";

        } else {
            echo "Fehler beim Hochladen der Zusammenfassung.";
        }

        $stmt->close();


    $conn->close();
}
?>
Tags:

2

Answers


  1. 0

    Your code uses incorrect data type binding for LONGBLOB. The correct type to use is "s" for string when binding binary data.

    // Correct the bind_param line to use "s" for binding LONGBLOB data
$stmt->bind_param("iis", $schuelerId, $buchId, $dateiDaten);
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  2. 0

    You only really need to use the b/blob bind in mysqli if the row data you’re sending is, in aggregate, larger than your mysql server’s configured max_allowed_packet. When using this bind type you must set the value to null and then use mysqli_stmt::send_long_data() like so:

    $stmt = $mysqli->prepare("INSERT INTO messages (message) VALUES (?)");
$null = NULL;
$stmt->bind_param("b", $null);
$fp = fopen("messages.txt", "r");
while (!feof($fp)) {
    $stmt->send_long_data(0, fread($fp, 8192));
}
fclose($fp);
$stmt->execute();

    The above example is lifted from the linked doc, but the key points are to bind a null variable, use a chunk size smaller than the configured max_allowed_packet [8192 in this example], and call send_long_data() as many times as necessary to power through the data.

    If you are certain that your data will always be smaller than max_allowed_packet then the much simpler answer is to use an s/string bind as suggested by @suchislife.

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