Submitting a form to a hidden frame allows you to keep the visitor on the same page while the work is being done in the background. The form is set to submit to the same URL and its target attribute points to a hidden iframe element. The “status” div will display the numeric value of the percent uploaded. The div with the ID “bar_color” will be dynamically updated as the file upload progresses. The div with the ID “bar_blank” is the container for the progress bar. If you’re interested in what such code should look like, check out the article File Uploads with PHP by Timothy Boronczyk.Īfter the head section which provides the page’s title and includes the stylesheet, you’ll notice a small collection of div elements. In the example the code to actually process the file has been omitted to keep things simple. Id="myForm" enctype="multipart/form-data" target="hidden_iframe"> Additionally, I won’t bother saving the file after it has been uploaded. Just to keep things as simple as possible, the example will post to itself and only handle one file upload at a time. The first file I’ll present is the upload form. Make sure the settings in your php.ini file allow large uploads, specifically the post_max_size and upload_max_filesize directives, and then verify they are sane values when you go to production. In this case, you might want to try transferring a large file. When you are developing either locally or on a fast network and upload small files, you won’t be able to visually observe the progress because the transfer happens so fast. The print_r() output of the $_SESSION array will look similar to the following during a file transfer: Array When session.upload_progress.enabled is true (as it is by default in PHP 5.4 and presumably beyond) and $_POST is sent during an upload, information about the file transfer is made available in the $_SESSION superglobal array. The session.upload_progress.enabled directive must be enabled and there must be a hidden field in your web form with the name specified by the session.upload_progress.name directive. I’ll first discuss how it works, and then I’ll walk you through creating the four files needed to accomplish the task (an upload form, some JavaScript, a little CSS, and a file to return the status of the upload).īesides the usual requirements to allow file uploads, there are two more to track the progress. In this article I’ll show you how this feature can be used to create a simple upload progress bar without any external libraries or browser dependencies. As of PHP 5.4, they’ve done it again with a new set of configuration directives, session.upload_progress. One of the many reasons I love PHP is that it makes seemingly difficult tasks easy. But in the words of Yoda, “No… There is another.” It would seem as though all the options are fraught with nuisances and the task has quickly become a headache. Yet another solution is to install the Alternative PHP Cache extension, but that may not be available depending on your hosting environment and it seems like overkill for such a small task such as this. An alternate solution is to rely on a Flash, Java, or ActiveX plugin no thanks, I’ll pass. Unfortunately, HTML5 still isn’t a completed standard yet and isn’t uniformly supported across all browsers. JavaScript can access a file’s name, type, and even the width and height of a local image, but it wasn’t until HTML5 that it could access a file’s size. On second thought, you’d find things aren’t quite that simple. At first thought, you might think accomplishing this can be done easily by first obtaining the file’s size from the user’s computer and then performing some simple calculations against the directory on the server where the file is being uploaded to.
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