服务器端已经写了处理的代码，为什么提示方法不允许？

module.exports = {
 uploadcsv: function *(next) {
    console.log('进入上传文件');
    console.log('this.method:' + this.method);
    if ('POST' != this.method) {
      return yield next;
    }

    var parts = parse(this),
        part;

    while (part = yield parts) {
      console.log('进入循环');
      console.log('part:' + part);
      var stream = fs.createWriteStream('/tmp/' + Math.random());
      part.pipe(stream);
      console.log('uploading %s -> %s', part.filename, stream.path);
    }
    this.redirect('/detailbase');
 }
}