php - rand() update image with the name of the previous one - php

Question

I have a table CRUD that display my database.
When I upload an image in my image folder I generate a random name of numbers with that function rand()
Here is what I have coded :
My upload function
function importer_image()
{
if(isset($_FILES["image"]))
{
$extension = explode('.', $_FILES['image']['name']);
$new_name = rand() . '.' . $extension[1];
$destination = './upload/' . $new_name;
move_uploaded_file($_FILES['image']['tmp_name'], $destination);
return $new_name;
}
}
My upload php
if($_POST["operation"] == "Ajouter")
{
$image = '';
if($_FILES["image"]["name"] != '')
{
$image = importer_image();
}
The problem is then when I code the update function, the substitued image stays in my folder and the new one has a new name generated. In order to avoid this, I would like to create a condition that says if $image !='' 1/ erase the old file 2/ upload the new file and keep the same name than the deleted image.
So I'm trying to create an update php process that would 1/ delete unlink() 2/ upload the new image with the name of the previous image.

Answer 1

In order to delete the old image and maintain new name of image as previous, you have to take a hidden input in your form which contain your uploaded image name.
For e.g :
<input type="hidden" name="old-image" value="here is your previous image">
Now when your upload function will hit then you can get previous image name by request and can delete or maintain new image as previous.
if($_FILES['image']['name'] != '') {
$old_image = $_POST['old-image']; // get old image
$new_name = $old_image; // make new image name as previous
unlink('/upload/'.$old_image); // remove old image from folder
$destination = './upload/' . $new_name;
move_uploaded_file($_FILES['image']['tmp_name'], $destination);
return $new_name;
} else {
//if there is no image uploaded in the form then it will maintain old image
return $new_name= $_POST['old-image'];
}
Hope it will help you.

Answer 2

Your code to get extension works only if you have just one dot in the uploaded filename, it won't work for example on image_a.1.jpg. Use instead:
$extension = strrchr($_FILES['image']['name'],'.');
Also, using rand() for naming will eventually give you a headache when it generates the same number the second time and the uploaded image will overwrite the old one or not get saved, possibly producing error showing the user your full server save path. I'd use some hashing, like:
$new_name = md5($_FILES['image']['name'] . time());
If you need to save the file name as int, use crc32() instead of md5(). You could convert md5() result to int, but that would produce a very long int (128bit) that might not fit in your database or even PHP code.