Create Unique Image Names

Question

What's a good way to create a unique name for an image that my user is uploading?

I don't want to have any duplicates so something like MD5($filename) isn't suitable.

Any ideas?

Answer 1

Something like this could work for you:

while (file_exists('/uploads/' . $filename . '.jpeg')) {
   $filename .= rand(10, 99);
}

Answer 2

http://php.net/manual/en/function.uniqid.php maybe?

• You can prefix it with the user id to avoid collisions between 2 users (in less than one millisecond).

Answer 3

For good performance and uniqueness you can use approach like this:

• files will be stored on a server with names like md5_file($file).jpg

• the directory to store file in define from md5 file name, by stripping first two chars (first level), and second two (second level) like that:

  uploaded_files\ 30 \ c5 \ 30 c5 67139b64ee14c80cc5f5006d8081.pdf

• create record in database with file_id, original file name, uploaded user id, and path to file on server

• on server side create script that'll get role of download providing - it'll get file by id from db, and output its content with original filename provided by user (see php example of codeigniter download_helper ). So url to file will look like that:

  http://site.com/download.php?file=id

---

Pros:

• minified collisions threat

• good performance at file lookup (not much files in 1 directory, not much directories at the same level)

• original file names are saved

• you can adjust access to files by server side script (check session or cookies)

Cons:

• Good for small filesizes, because before user can download file, server have to read this file in memory

Answer 4

For short names:

$i = 0;
while(file_exists($name . '_' . $i)){
  $i++;
}

WARNING: this might fail on a multi threaded server if two user upload a image with the same name at the same time. In that case you should include the md5 of the username.

Answer 5

lol there are around 63340000000000000000000000000000000000000000000000 possibility's that md5 can produce plus you could use just tobe on the safe side

$newfilename = md5(time().'image');
if(file_exists('./images/'.$newfilename)){
    $newfilename = md5(time().$newfilename);
}
//uploadimage

Answer 6

try this file format:

$filename = microtime(true) . $username . '.jpg';