How to replace old file with new file in codeigniter? - php

Question

I am using unlink to remove old file with new file, but it doesn't work. Please help me, I'm a new programmer and really stuck with this.
here's my code
if ($data['upload_spk'] = "") {
$config['upload_path'] = './assets/upload';
$config['allowed_types'] = 'jpg|png|pdf';
$this->load->library('upload', $config);
if (!$this->upload->do_upload('upload_spk')) {
echo "upload gagal";
die();
} else {
$data['upload_spk'] = $this->upload->data('file_name');
$id_ajukan = $this->input->post('id_ajukan');
$query = $this->db->get('ajukan_keluhan', array('id_ajukan' => $id_ajukan));
$ambil = $query->row()->upload_spk;
unlink('./assets/upload/' . $ambil);
}
} else {
if ($_FILES['upload_spk']['name'] != "") {
$config['upload_path'] = './assets/upload';
$config['allowed_types'] = 'jpg|png|pdf';
$this->load->library('upload', $config);
if (!$this->upload->do_upload('upload_spk')) {
echo "upload gagal";
die();
} else {
//upload_spk diubah
$data['upload_spk'] = $this->upload->data('file_name');
$id_ajukan = $this->input->post('id_ajukan');
$query = $this->db->get('ajukan_keluhan', array('id_ajukan' => $id_ajukan));
$ambil = $query->row()->upload_spk;
unlink('./assets/upload/' . $ambil);
}
} else {
$data['upload_spk'] = $this->input->post('lama');
}
}
and this is code in view
<div class='form-group row'> <label for='uploadsp' class='col-sm-2 col-form-label'>Upload SP/SPK</label> <div class='col-sm-10' align='left'> <input type='file' class='form-control col-md-10' cols='10' rows='5' name='upload_spk' / accept='.jpg, .png, .pdf/*'><input type='hidden' id='lama' name='lama' value='<?= $kelola_tiket->upload_spk ?>'> </div> </div>