OpenERP 7：如何将解码文件作为CSV文件打开？

I have a module which asks the user to give a csv file, with the binary field. So once the module has it, I decode it and write the result in a Temporary File, but then I can't open it as a CSV file : I will get the error "TypeError: coercing to Unicode: need string or buffer, file found" because I'm trying to open a File Object. So how can I decode the file and then open it as a CSV file ?I have a module which asks the user to give a c