How to Multiple File Upload with Insert Batch in CodeIgniter?

PHP Code:

   public function newphoto($id){
        // Check Login
          if(!$this->session->userdata('user_id')){
             // Redirect to page
             redirect('users/login');
         }
     
         // Field Rules
         $this->form_validation->set_rules('title', 'Title', 'trim');
     
         if ($this->form_validation->run() == FALSE) {
     
             // Set error message
             $this->session->set_flashdata('error', 'You must select one or more images');
     
             // Redirect
             redirect('users/album/'.$id.'/'.$this->session->userdata('username'));
     
         } else {
     
             // Multiple File Upload
             $data = array();
             if($this->input->post('mysubmit') && !empty($_FILES['post_image']['name'])){
                 $filesCount = count($_FILES['post_image']['name']);
                 for($i = 0; $i < $filesCount; $i++){
     
                     $file_name = 'post_image[]';
     
                     $_FILES[$file_name]['name'] = $_FILES['post_image']['name'][$i];
                     $_FILES[$file_name]['type'] = $_FILES['post_image']['type'][$i];
                     $_FILES[$file_name]['tmp_name'] = $_FILES['post_image']['tmp_name'][$i];
                     $_FILES[$file_name]['error'] = $_FILES['post_image']['error'][$i];
                     $_FILES[$file_name]['size'] = $_FILES['post_image']['size'][$i];
     
                     // Create user folder
                     $folder = $this->session->userdata('username');
     
                     // Upload Status Image
                     $config['upload_path'] = 'assets/img/users/media/'.$folder.'/';
                     $config['allowed_types'] = 'gif|jpg|png|jpeg';
                     $config['max_size'] = 0;
                     $config['encrypt_name'] = TRUE;
                     $config['remove_spaces'] = TRUE;
                     $config['detect_mime'] = TRUE;
                     $config['mod_mime_fix'] = TRUE;
     
                     $this->load->library('upload', $config);
                     $this->upload->initialize($config);
     
                     // If username folder does not exist, create it
                     if(!is_dir($config['upload_path'])) {
                         mkdir($config['upload_path'], 0777, TRUE);
                     }
     
                     // If files selected send them to ci_posts
                     if($this->upload->do_upload($file_name)){
     
                         $fileData = $this->upload->data('file_name');
                         $upload_data[$i]['post_image'] = $fileData;
     
                         $this->db->insert_batch('ci_posts', $upload_data);
     
                     }
     
                     // Get last post id for relationship data
                     $post_id = $this->db->insert_id();
     
                     // Relationship Array
                     $data[$i] = array(
                         'parent_id'   => $id,
                         'post_id'     => $post_id,
                         'user_id'     => $this->session->userdata('user_id'),
                         'status'      => 'published',
                         'type'        => 'user_media',
                     );
     
                     // Insert relationship
                     $this->db->insert_batch('ci_relationship', $data);

                    // Activity Array
                    $data = array(
                        'resource_id' => $id,
                        'type'        => 'user_media',
                        'action'      => 'added',
                        'user_id'     => $this->session->userdata('user_id'),
                        'message'     => 'A new photo by (' . $this->session->userdata('username') . ')'
                    );

                    // Insert Activity
                    $this->Activity_model->add($data);
     
                     // Set Message
                     $this->session->set_flashdata('success', 'Photo has been added');
     
                     // Redirect
                     redirect('users/album/'.$id.'/'.$this->session->userdata('username'));
     
                 }
             }
         }
     }

PHP Code:

                   <?php
                        $action = array(
                        );
                        $attributes = array(
                            'id'    =>  'user_form',
                            'class' =>  ''
                        );
                        $hidden = array();
                    ?>
                    <?= form_open_multipart('users/newphoto/'.$album->post_id, $attributes, $hidden); ?>
                        <!-- <div id="extraInputsContainer"></div> -->
                        <div class="input-group">
                            <label class="input-group-btn">
                                <span class="btn btn-warning">
                                    Browse 
                                    <?php $data = array(
                                            'id'    =>  'post_image',
                                            'name'  =>  'post_image[]',
                                            'class' =>  'form-control',
                                            'value' =>  set_value('post_image'),
                                            'style' =>  'display:none',
                                        ); ?>
                                        <?= form_upload($data, '', 'multiple'); ?>
                                </span>
                            </label>
                            <input type="text" class="form-control" readonly>
                        </div>
                        <hr>
                        <?php 
                            $args = array(
                                'id'    =>  'mysubmit',
                                'name'  =>  'mysubmit',
                                'class' =>  'btn btn-warning btn-sm',
                            );
                            $value = html_escape('Submit');
                            $extra = array(
                                'onclick'   =>  '',
                            );
                        ?>
                        <?= form_submit($args, $value, $extra); ?>
                    <?= form_close(); ?>