def download_barcodes_json(self,download_dir):
if not os.path.isdir(download_dir):<EOL><INDENT>os.makedirs(download_dir)  <EOL><DEDENT>res = dxpy.find_one_data_object(project=self.dx_project_id,folder=self.DX_QC_REPORT_FOLDER,name="<STR_LIT>",name_mode="<STR_LIT>")<EOL>dx_file = dxpy.DXFile(dxid=res["<STR_LIT:id>"],project=res["<STR_LIT>"])<EOL>download_file_name = os.path.join(download_dir,dx_file.name)<EOL>msg = "<STR_LIT>".format(filename=dx_file.name,download_dir=download_dir)<EOL>debug_logger.debug("<STR_LIT>" + msg)<EOL>dxpy.bindings.dxfile_functions.download_dxfile(dxid=dx_file,filename=download_file_name)<EOL>success_logger.info("<STR_LIT>" + msg)<EOL>return download_file_name<EOL>
Downloads the run_details.json and the barcodes.json from the DNAnexus sequencing results project.

Args:
    download_dir: `str` - The local directory path to download the QC report to.

Returns:
    `str`. The filepath to the downloaded barcodes.json file.