How to upload images and implement specific naming rules in PHP

PHP is a very popular programming language that is used to develop many web applications. Image uploading is one of the common functions in web applications. Usually we need to rename the uploaded images or use specific naming rules.

This article will introduce how to upload images in PHP and implement specific naming rules.

1. Basic image upload

First, we need to create a form to accept users to upload files. The form should contain a file input element, submit button and an action attribute pointing to the PHP script that handles the upload.

<form action="upload.php" method="post" enctype="multipart/form-data">
    <input type="file" name="fileToUpload" id="fileToUpload">
    <input type="submit" value="Upload Image" name="submit">
</form>

The above code tells the browser that the data needs to be encoded as "multipart/form-data" when submitting the form. This encoding method can be used for uploading files.

Below is the PHP code that handles the upload, where we will implement the rename rule.

<?php
$target_dir = "uploads/";
$target_file = $target_dir . basename($_FILES["fileToUpload"]["name"]);
$uploadOk = 1;
$imageFileType = strtolower(pathinfo($target_file,PATHINFO_EXTENSION));

// Check if image file is a actual image or fake image
if(isset($_POST["submit"])) {
    $check = getimagesize($_FILES["fileToUpload"]["tmp_name"]);
    if($check !== false) {
        echo "File is an image - " . $check["mime"] . ".";
        $uploadOk = 1;
    } else {
        echo "File is not an image.";
        $uploadOk = 0;
    }
}

// Check if file already exists
if (file_exists($target_file)) {
    echo "Sorry, file already exists.";
    $uploadOk = 0;
}

// Check file size
if ($_FILES["fileToUpload"]["size"] > 500000) {
    echo "Sorry, your file is too large.";
    $uploadOk = 0;
}

// Allow certain file formats
if($imageFileType != "jpg" && $imageFileType != "png" && $imageFileType != "jpeg"
&& $imageFileType != "gif" ) {
    echo "Sorry, only JPG, JPEG, PNG & GIF files are allowed.";
    $uploadOk = 0;
}

// Check if $uploadOk is set to 0 by an error
if ($uploadOk == 0) {
    echo "Sorry, your file was not uploaded.";
// if everything is ok, try to upload file
} else {
    if (move_uploaded_file($_FILES["fileToUpload"]["tmp_name"], $target_file)) {
        echo "The file ". basename( $_FILES["fileToUpload"]["name"]). " has been uploaded.";
    } else {
        echo "Sorry, there was an error uploading your file.";
    }
}
?>

2. Specific file naming rules

Now, we will modify the PHP code to implement renaming rules based on the current date and time.

<?php
$target_dir = "uploads/";
$timestamp = date("YmdHis");
$target_file = $target_dir . $timestamp . '.' . pathinfo($_FILES["fileToUpload"]["name"], PATHINFO_EXTENSION);
$uploadOk = 1;
$imageFileType = strtolower(pathinfo($target_file,PATHINFO_EXTENSION));
...

In this example, we store the current date and time in the $timestamp variable. We then rename the uploaded files to $timestamp.extension to ensure each uploaded file has a unique name.

3. Naming rules that keep the original file name but add a prefix

Now, we will modify the PHP code to implement the renaming rule that keeps the original file name, but adds a prefix.

<?php
$target_dir = "uploads/";
$prefix = "myprefix_";
$target_file = $target_dir . $prefix . basename($_FILES["fileToUpload"]["name"]);
$uploadOk = 1;
$imageFileType = strtolower(pathinfo($target_file,PATHINFO_EXTENSION));
...

In this example, we add the predefined prefix variable to the original name of the uploaded file. This will produce filenames prefixed with "myprefix_".

Summary:

It is easy to implement file upload and rename in PHP. This article demonstrates how to rename uploaded files based on the current date and time or adding a prefix. You can modify the code to implement different renaming rules according to your needs. After uploading the file, you can also save it to a database or create a thumbnail. Hope this article helps you!

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