Parameters: {"utf8"=>"✓", "authenticity_token"=>"uyR6AK1iXhExxiLiDu3PBC1RALCTjtkZIN37nUOBGLk=", "record"=>{"op_platform"=>"", "select_location"=>"", "actual_weight"=>"1.0", "excel"=>#<ActionDispatch::Http::UploadedFile:0xd44bdf0 @original_filename="文件.xls", @content_type="application/vnd.ms-excel", @headers="Content-Disposition: form-data; name=\"record[excel]\"; filename=\"\xE5\x88\x86\xE6\x8B\xA3\xE5\x8D\x95_20151127095756.xls\"\r\nContent-Type: application/vnd.ms-excel\r\n", @tempfile=#<File:/tmp/RackMultipart20151127-21761-zrgawx>>}, "commit"=>"Update", "association"=>"select_items", "iframe"=>"true", "parent_scaffold"=>"buyer/select_lists", "select_list_id"=>"1", "id"=>"1"}

比如要获取 excel 的 @originnal_filename 等属性，该用 params[??] 来获取啊？