Announcement

Collapse
No announcement yet.

New In PHP--Image Databasing

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • New In PHP--Image Databasing

    This tutorial teaches you how to upload images into a mysql database using PHP. Even though it sounds complicated, it is fairly simple and has many practical applications. One example of an application would be Forum User Images. Take user avatars for example. Its impractical to upload avatar files to one common folder, because chances are sooner or later two users will have the same name for an avatar, and either one avatar will be overwritten, or the other not accepted, causing trouble. Image Databasing solves this problem by inserting the image data into its own unique row in a table, each assigned with an ID number instead of a filename. Images can then be called from the database and be view using one php file for all images. How are they inserted into the database? By converting the data to base64. If your confused, please bear with me, you will understand it soon.

    There will be 3 PHP files in this tutorial:

    readdir.php - this puts all the images in a folder into the database
    image.php - the actual image script that displays the imag
    view.php - an example file that shows you how to call the image
    Creating the Image Database

    First, create a mysql database called base64imgdb (this is the name that will be used throughout the tutorial)
    Second, create a table called images with two rows. Name the first one imgid, and give it the parameters TYPE: INT EXTRA: auto_increment, and check the circle under Primary. Name the second sixfourdata, and make it TYPE: LONGTEXT. Here is the sql code:

    CREATE TABLE `images` (
    `imgid` INT NOT NULL AUTO_INCREMENT ,
    `sixfourdata` LONGTEXT NOT NULL ,
    PRIMARY KEY ( `imgid` )
    );

    The READDIR.PHP script

    This script reads a directory within the server, selects all the jpg and gif images, encodes them into base64, and uploads them to the database, except in a different order. This is because the script reads each image in a loop, and we would like to keep a constant connection to the mysql database instead of creating multiple ones. Here is the database connection where username and password need to be changed:

    <?
    $dbcnx=
    mysql_connect("localhost", "username", "password");
    mysql_select_db("base64imgdb");
    ?>

    Next we need to open the directory, where "./" s the directory the readdir.php file is located:

    $path = "./";
    $dir_handle = opendir($path) or
    die("Unable to open directory $path");

    This is the hardest part of the script: sorting the image types, reading the data using fopen, converting it using base64_encode, and then inserting it into the table.

    <?
    while ($file = readdir($dir_handle)) {
    $filetyp = substr($file, -3);
    if ($filetyp == 'gif' OR $filetyp == 'jpg') {
    $handle = fopen($path . "/" . $file,'r');
    $file_content =
    fread($handle,filesize($path . "/" . $file));
    fclose($handle);
    $encoded = chunk_split(base64_encode($file_content));
    $sql = "INSERT INTO images SET sixfourdata='$encoded'";
    mysql_query($sql);
    }
    }
    ?>

    This is the last and final part of the readdir.php: closing the directory and stating the proccess is complete:

    <?
    closedir($dir_handle);
    echo("complete");
    mysql_close($dbcnx);
    ?>

    The Image Reader IMAGE.PHP

    This file may be the hardest file to understand whenever you see how simple view.php is, but bear with me, your patience will pay off. This file takes a request, requests the row in the table, decodes the data, and presents itself as an image. First, we have to connect to the database again:

    <?
    $dbcnx=mysql_connect("localhost","username","passw ord");
    mysql_select_db("base64imgdb");
    ?>

    Now we need to find out which row its requesting, which is done using image.php?img=x:

    <?
    $img = $_REQUEST["img"];
    ?>

    After this, we need to connect to the table, get the data, and set it into variables:

    <?
    $result = mysql_query("SELECT * FROM images WHERE imgid=" . $img ."");
    if (!$result) {
    echo("<b>Error performing query: " . mysql_error() . "</b>");
    exit();
    }
    while ($row = mysql_fetch_array($result)) {
    $imgid = $row["imgid"];
    $encodeddata = $row["sixfourdata"];
    }
    ?>

    Now here is the last and most confusing part of the file:

    <?
    mysql_close($dbcnx);
    echo base64_decode($encodeddata);
    ?>

    Now let me explain this. All this does is decodes the base64-encoded image data, end echos it. Thats it, nothing else. "Let me see the picture already!" VIEW.PHP (example viewer) Okay, so you made it this far already. This is now the easiest to copy and paste but hardest part to understand, where image.php?img=1matches with whatever row the image is on, for example if its row 357 then you would need to put image.php?img=357:

    <img src='image.php?img=1' border="0" alt="">

    Now that wasnt so hard was it? But most of you are probably wondering why when you link to a page, you get an image. This is the reason: images arent defined by their 3 letter suffixes (such as jpg or gif), but by how their headers are written. IMAGE.PHP simply echos the image data, and acts like an image even though it just proccesses the request. This is why you get an image.

    The files please!

    readdir.php:

    <?
    ###############################
    # DB CONNECTION
    # CHANGE THESE VALUES
    ###############################
    $dbcnx = mysql_connect("localhost", "username", "password");
    mysql_select_db("base64imgdb");

    $path = "./";
    $dir_handle = opendir($path) or die("Unable to open directory $path");

    while ($file = readdir($dir_handle)) {
    $filetyp = substr($file, -3);
    if ($filetyp == 'gif' OR $filetyp == 'jpg') {
    $handle = fopen($file,'r');
    $file_content = fread($handle,filesize($file));
    fclose($handle);
    $encoded = chunk_split(base64_encode($file_content));
    $sql = "INSERT INTO images SET sixfourdata='$encoded'";
    mysql_query($sql);
    }
    }

    closedir($dir_handle);
    echo("complete");
    mysql_close($dbcnx);
    ?>

    image.php:

    <?
    $dbcnx = mysql_connect("localhost", "username", "password");

    mysql_select_db("base64imgdb");

    $img = $_REQUEST["img"];

    $result = mysql_query("SELECT * FROM images WHERE imgid=" . $img . "");
    if (!$result) {
    echo("<b>Error performing query: " . mysql_error() . "</b>");
    exit();
    }
    while ($row = mysql_fetch_array($result) ) {
    $imgid = $row["imgid"];
    $encodeddata = $row["sixfourdata"];
    }
    mysql_close($dbcnx);
    echo base64_decode($encodeddata);
    ?>

    And view.php (i shouldnt need to post this..)

    <html>
    <body>
    ..
    <img src='image.php?img=1' border="0" alt="">
    ..
    </body>
    </html>
Working...
X