[RESOLVED] File Upload Generate a name

@firmanAug 11.2006

I have a form where I upload a file. I would like to create a RANDOM name for all the files uploaded that does not repeat….yet only about 10-20 alpha-numeric combination long. Also.. I need to get the .extention off of the file so I know what kind is uploaded to attach to the end of the name. What is the best way to go about this?

basically I have me_and_her.jpg

I upload the file

then want a random_name.jpg to save it to my server.

to post a comment

PHP

19 Comments(s) _↴

@sitehatcheryAug 11.2006 — #Here's a very rough outline of one way to approach this:

1. read the extension off of the filename.

2. generate a random name.

3. attach the file extension to the random name that contains 10-20 alpha-numeric characters

4. read through the file upload directory.

5. compare each file in the upload directory with the generated random name.

6. if a match exists, go back to step 2.

7. if a match does not exist, you're in luck. Use the randomly generated name.

Another option is to read all the files into an array. Then use the in_array() function to see if the auto generated file name + extension exists in the array. If it exists, generate another number.

There may be a more efficient way of doing it, but hopefully this gets some dialog on the subject going.

@PineSolPirateAug 11.2006 — #Here's the code I use for this sort of thing.

[code=php]$extension = $_FILES['document']['name']{strlen($_FILES['documentField']['name'])-3};
 
 $target = "/path/to/files/";
 $target .= rand(0, 100000);
 $target .= $extension;
 
 while (file_exists($target))
 {
 $target = "/path/to/files/";
 $target .= rand(0, 100000);
 $target .= $extension;
 }
 move_uploaded_file($_FILES['documentField']['tmp_name'],$target);[/code]

Should be good for about 100000 files.

This should be more efficient since you only have to check the filename a few times before you get a match.

@PineSolPirateAug 11.2006 — #I also bet you could use [url=http://us3.php.net/manual/en/function.md5-file.php]MD5_file[/url] for nice, unique names that will alert you to duplicate uploads. That'd be even better!

@firmanauthorAug 11.2006 — #Thank you for these suggestions so far... How about a random 10-20 digit alpha-numeric name?

@sitehatcheryAug 11.2006 — #

[code=php]
 $ranLen=rand(10,20);
 $getVal ="0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
 $ranFileName="";
 for ($i=1; $i<=$ranLen; $i++) {
 $ranFileName.= substr($getVal, rand(0,(strlen($getVal)-1)), 1);
 $ranFileName.=$extension;
 }
 [/code]

@sitehatcheryAug 11.2006 — #Will this work for you?

[code=php]
 $extension = $_FILES['document']['name']{strlen($_FILES['documentField']['name'])-3};
 $target = "/path/to/files/"; 
 
 function randomFile($extension, $target){
 $ranLen=rand(10,20);
 $getVal ="0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
 $ranFileName="";
 for ($i=1; $i<=$ranLen; $i++) {
 $ranFileName.= substr($getVal, rand(0,(strlen($getVal)-1)), 1);
 $file=$target.$ranFileName.$extension;
 }
 
 if(file_exists($file)){
 randomFile($extension, $target);
 }
 else{
 return $file;
 } 

 } 
 
 move_uploaded_file($_FILES['documentField']['tmp_name'], randomFile($extension, $target)); 
 [/code]

@bokehAug 11.2006 — #I hate random because it causes collisions. Why not just use [I]time()[/I]? It ten digits long and you could upload one file a second between now and 2037 without any chance of running out of file names.

@firmanauthorAug 12.2006 — #can you explain the time thing a little further? and why would 2037 collide?

@bokehAug 12.2006 — #[code=php]$filename = time() . '.jpg';[/code]

2037 is when the present timestamping system will run out of numbers.

@sitehatcheryAug 12.2006 — #You don't have to worry about collisions with this randomFile() function. With variable number of characters (10-20) with uppercase, lowercase, and numbers in random order, it's very unlikely that a duplicate will occur. In the rare ocassion that a duplicate would occur (better chance of winning the lottery), the function calls itself and is run again.

Oh, and I'd replace the extension getter code with this function:

[code=php]
 function getExtension($file){
 $exArray=explode(".", $file);
 $arrCount=count($exArray);
 $extension='.'.$exArray[$arrCount-1];
 return $extension;
 }
 [/code]

@bokehAug 12.2006 — #Random filenames are another branch of unmaintainable code. A logical naming convention is always going to be better than leaving your filenames to chance.

@balloonbuffoonAug 12.2006 — #Yeah, I use time() for my uploaded filenames, and it gives you an added bonus of knowing exactly when it was uploaded.

--Steve

@balloonbuffoonAug 12.2006 — #And for getting an extension, you can just use this:
[code=php]$extension = pathinfo($filename, PATHINFO_EXTENSION);[/code]
--Steve

@NogDogAug 12.2006 — #Guess I was bored -- here's a function using microtime to make sure we don't get any duplicates. It also uses getimagesize() if available to determine the image type, if applicable.

[code=php]
 function unique_file_name($file)
 {
 $suffix = '';
 if(function_exists("getimagesize") and is_readable($file))
 {
 $info = getimagesize($file);
 if($info[2])
 {
 $types = array(1 => 'gif', 'jpg', 'png', 'swf', 'psd', 'bmp', 'tiff', 
 'tiff', 'jpc', 'jp2', 'jpx', 'jb2', 'swc', 'iff', 'wbmp', 'xbm');
 $suffix = $types[$info[2]];
 }
 }
 if($suffix == '')
 {
 $name = basename($file);
 $parts = explode(".", $name);
 $suffix = (count($parts) > 1) ? strtolower(array_pop($parts)) : '';
 }
 list($usec, $sec) = explode(' ', microtime());
 $filename = date("YmdHis") . str_replace('0.', '', sprintf("%.6f", $usec));
 $filename .= ($suffix == '') ? '' : ".$suffix";
 return($filename); 
 }
 [/code]

@firmanauthorAug 12.2006 — #And for getting an extension, you can just use this:
[code=php]$extension = pathinfo($filename, PATHINFO_EXTENSION);[/code]
--Steve[/QUOTE]

How does the above work?

@balloonbuffoonAug 14.2006 — #Sorry, late reply, but did you look in the manual for [url=php.net/pathinfo]pathinfo[/url]?

--Steve

@sitehatcheryAug 15.2006 — #I know you're already done, but here is a unique id that is based on the current time. By default it is 23 characters long. if you add 'true' as the second paramenter, it will add an additional 9 characters.

uniqid(time(), true);

@balloonbuffoonAug 15.2006 — #Interesting, I rather like that uniqid() function!

--Steve

@Phill_PaffordAug 18.2006 — #function guid()

{

if (function_exists('com_create_guid'))

{

return com_create_guid();

}

else

{

mt_srand((double)microtime()*10000);//optional for php 4.2.0 and up.

$charid = strtoupper(md5(uniqid(rand(), true)));

$hyphen = chr(45);// "-"

$uuid = substr($charid, 0, 8).$hyphen

.substr($charid, 8, 4).$hyphen

.substr($charid,12, 4).$hyphen

.substr($charid,16, 4).$hyphen

.substr($charid,20,12);

return $uuid;

}

}

I use this and it works great!

Also in #PHP _↴

real simple. how do i send forms as a .txt attachment?SMTP and phpmailer Prefill form field from database/login

Success!

Help @firman spread the word by sharing this article on Twitter...

Tweet This

[RESOLVED] File Upload Generate a name

19 Comments(s) _↴

Also in #PHP _↴

Success!

Social

Version

[RESOLVED] File Upload Generate a name

19 Comments(s) ↴

Also in #PHP ↴

Success!

The web is an endless sea of information. Don't miss the boat... Subscribe!

Social

Version

19 Comments(s) _↴

Also in #PHP _↴