我试图上传一个视频使用codeigniter 3.但为什么我得到了一个错误**“列'文件'不能为空”**我已经检查了我的代码，没有错。请帮助我。这里是我的代码

型号

public function savevideo(){
    $post = $this->input->post();
    $this->file = $this->UploadVideo();
    return $this->db->insert($this->_tableigavideo, $this);
 }
 private function UploadVideo(){
    $config['upload_path']          = './video';
    $config['allowed_types']        = 'MP4';
    $config['overwrite']            = true;
    $config['max_size']             = 17500000; 

    $this->load->library('upload', $config);

    if ($this->upload->do_upload('file')) {
        return $this->upload->data("file_name");
    }
}

这是我的控制器

public function addvideo(){
    $indikator = $this->IndikatorModel;
    $validation = $this->form_validation;
    $validation->set_rules($indikator->rules());

    if ($validation->run() == TRUE){
     $indikator->savevideo();
     $this->session->set_flashdata('success', 'Berhasil upload video');
     redirect('indikator/index/'.$idiga);
    }
}

这是我的观点

<label class="col-form-label col-sm-3" for="file"><b>Pilih File Mp4/Mov</b></label>
      <div class="col-sm-9">
        <input type="file" name="file" accept=".mp4">
      </div>