Django:带有文件对象和更新字段值的Httpresponse。

I'm having trouble with saving/updating a value to my database table after the Httpresponse is created and am looking for any tips, help, pointers, etc. I am passing a pdf object from my database to the browser, which works perfectly when the updating code is not in the model. With the code as below, I get a Django Unicode Decode Error. The exception states : "'utf8' codec can't decode bytes in position 564-565: invalid data." The odd thing is that this error does not occur when I am not trying to update the pdf_printed field (meaning no decoding error occurs normally, I get the pdf object to display without this problem), so wondering if those two methods are somehow clashing... seems like the obj.save may be the issue. Again, thanks for any insight to this issue!I'm having trouble with saving/updating a value