Module Prestashop 1.7 : Custom image upload always replaced - prestashop

Question

My file_url field is always erased in Database if I don't select it. (even if an image is already integrated)
If I click Save in this situation, the field PC Image is deleted.
Here is my postImage() method in my AdminCustomController
protected function postImage($id)
{
$file = isset($_FILES['file_url']) ? $_FILES['file_url'] : false;
if ($file && is_uploaded_file($file['tmp_name'])) {
$path = _PS_MODULE_DIR_ . 'custom/img/';
$tmp_arr = explode('.', $file['name']);
$filename = $file['name'];
if (!Tools::copy($file['tmp_name'], $path . $filename)) {
$errors[] = Tools::displayError('Failed to load image');
}
}
}
And here is the renderForm()
public function renderForm()
{
$image_url = '';
if($this->object->file_url) {
$image_url = ImageManager::thumbnail(
_PS_MODULE_DIR_ . 'homecase/img/' . $this->object->file_url,
$this->table . $this->object->file_url,
150,
'jpg',
true,
true
);
}
$this->fields_form = [
//Entête
'legend' => [
'title' => $this->module->l('Edition'),
'icon' => 'icon-cog'
],
array(
'type' => 'file',
'label' => $this->l('PC Image'),
'name' => 'file_url',
'display_image' => true,
'image' => $image_url ? $image_url : false,
),
....
The upload and the save in DB is OK. But when the image exists and I don't select an other in the field. The file_url field is erased in the DB.
Could you help me?
Thanks !

Answer 1

You need to check if an image was uploaded and only after that update your DB records. So, just try to add return false; to your postImagemethod and that check before your DB update like
if ($this->postImage($id) !== false){
//update image record
}