今天学习CI框架的上传，照着文档上的配置方法一直上传不了，一直报错：

The upload path does not appear to be valid

前端：

<div class="form-group">
        <label class="col-sm-3 control-label">微信</label>
       <div class="col-sm-5">
        <input type="text" name="weixin" id="weixin">
       </div>
</div>

后台：

public function upload_pic()
{
    $config['upload_path']      = './uploads';
        $config['allowed_types']    = 'gif|jpg|png|jpeg';
        $config['max_size']     = 100;
        $config['file_name']=time().mt_rand(1000,9999);
        $this->load->library('upload',$config);
        $this->upload->initialize($config);
    $status=$this->upload->do_upload('weixin');

    $wrong=$this->upload->display_errors();
    if($wrong){
        p($wrong);
    }        
    $info=$this->upload->data();
}

百度，手册反复查了几遍都没解决，不经意的改了一下上传路径，居然就好了，被坑死。

$config['upload_path']      = 'uploads';   //去掉前面的“./”就好了，上传目录依然放在根路径下
$config['allowed_types']    = 'gif|jpg|png|jpeg';
$config['max_size']     = 100;
$config['file_name']=time().mt_rand(1000,9999);
$this->load->library('upload',$config);
$this->upload->initialize($config);