How to execute PHP code before a file is uploaded?

Hi,

My form looks like this:

<form enctype="multipart/form-data" action="upload.php" method="POST">
  <input type="hidden" name="MAX_FILE_SIZE" value="2000000" />
  <input name="photo[]" type="file" /><br />
  <input name="photo[]" type="file" /><br />
  <input name="photo[]" type="file" /><br />
  <input name="photo[]" type="file" /><br />
  <input name="photo[]" type="file" /><br />
  <input name="photo[]" type="file" /><br />
  <input name="photo[]" type="file" /><br />
  <input name="photo[]" type="file" /><br />
  <input name="photo[]" type="file" /><br />
  <input name="photo[]" type="file" /><br />
  <input type="submit" value="Upload" />
</form>

And I can process the uploaded files without any problems. But the processing doesn't seem to happen until after all the files are uploaded. I would like to execute some code (hopefully) before each file is sen tby the client.

Thanks,
Rei.

What do you have for your upload.php?

No there is no way to execute php-code before the complete POST-request (and thus the uploaded files) are completly send to the webserver. Then the php-engine starts to work if all data was send to the webserver. Else there would be a command which can be used to check if a file is completly uploaded or if that upload-process is still running.

Here's a snippet of the code that I'm currently using to process the files.

      foreach ($_FILES["photo"]["error"] as $key => $error){
        if ($error == UPLOAD_ERR_OK){
          $tmp_name = $_FILES["photo"]["tmp_name"][$key];
          $upload_file = "./" . $upload_dir . "/" . $tmp_name;
          if(move_uploaded_file($tmp_name, $upload_file)){
            echo "File ".$_FILES["photo"]["name"][$key]." uploaded successfully. <br />";
          }
          else{
            echo "Error uploading ".$_FILES["photo"]["name"][$key].".<br />";
          }
        }
      }

If I can't execute code before the file is uploaded (i.e. after clicking the submit button) then is it possible after each file has finished uploading? Which begs another question: are files sent simultaneously or sequentially?

hernst42:

Then how do upload progress meters work?

Rei.

You can use flush();

This would echo your data before the whole process is finished.

foreach ($_FILES["photo"]["error"] as $key => $error){
        if ($error == UPLOAD_ERR_OK){
          $tmp_name = $_FILES["photo"]["tmp_name"][$key];
          $upload_file = "./" . $upload_dir . "/" . $tmp_name;
          if(move_uploaded_file($tmp_name, $upload_file)){
            echo "File ".$_FILES["photo"]["name"][$key]." uploaded successfully. <br />";
            flush();
          }
          else{
            echo "Error uploading ".$_FILES["photo"]["name"][$key].".<br />";
           flush();
          }
        }
      }

How upload progress works is a good question. Via plain HTML it is not possible, But with flash or java-appletes this can be done easyly, but HTML does not have the capability for that, maybe so JS can print a running bar while a frame is sending the data, but that does not start the processing on the server. I have never seen reliable progress meters, else such techniques would have been implemented in our projects.

About flush(): It does not work. The problem is how a HTTP-Request works from a Browser and how it is proccecced on the server-side. As said the php-engine start working AFTER all data has been passed from the Browser to the Webserver. The php-engine does not start and then waits if you want to access such a tempfile or where should php know that a file named xy is submitted to the webserver and put all information into $_FILES ??

So the only real progressbar indicating how many data is send is the progressbar of your browsers (if the browser has one). That the only programm that knows how many data has been send over the wire to server.

WoodyRoundUp:

I'm not so concerned about pushing any results to the browser before it has finished processing.

Do you know if this processing occurs after all uploaded data has been received by the server or at some stage before that?

Thanks,
Rei.

If you are doing your progress (not bar) from the server-side (which is your PHP file), then you could just simply use flush like what I mentioned above. The moment the flush() is called, your text that is echoed previously will be displayed as soon as possible.

> The progress is flushed to the user AFTER all data has been uploaded.
> The moment the flush() is called, your text that is echoed previously will be displayed as soon as possible.
Depends upon the output buffer (or ob) mode set in your php.ini file. On my server I have an ob of 8096 bytes. This means that data is sent to the user when 8096 bytes have been written to the ob. This can be overriden by calling flush() but only if this is enabled in your php.ini file. It is on my local server but not on my webhosts server.

Not to cloud the waters any more than they already are here, however I wanted to interject that there are in fact reliable upload progress bars avaialbale. They are written in perl because perl is able to access the raw POST data where PHP is not.


Alan