在codeigniter中没有上传图片

<form method="post" action="upload_image" enctype="multipart/form-data">
    <input type="file" name="image">
    <input type="submit" value="Upload">
</form>

public function upload_image()
{
    $config['upload_path'] = './uploads/'; // 设置上传文件的保存路径
    $config['allowed_types'] = 'gif|jpg|png'; // 允许上传的图片类型
    $config['max_size'] = 2048; // 允许上传的最大文件大小（单位：KB）

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

    if (!$this->upload->do_upload('image')) {
        // 上传失败，处理错误信息
        $error = $this->upload->display_errors();
        echo $error;
    } else {
        // 上传成功，处理上传后的文件信息
        $data = $this->upload->data();
        echo "File uploaded successfully: " . $data['file_name'];
    }
}