In python 3.4 multipart file upload breaks due to change in cgi.FieldStorage

[acv]

In Python 3.4, the cgi.FileStorage class now has a __del__ method that close the file objects.

BaseRequest.POST() uses that class to parse multipart requests and then grabs the files directly into FileUpload instances. When the function exits, the variable data is garbage collected and the __del__ method is called, closing the file handle held in the returned post dictionary.

Unit test test_environ.test_multipart() catches this because it tries to access the file object and read()s it which fails with this exception:

ValueError: I/O operation on closed file.

This doesn't happen in python 3.3.3.

I'm not sure the best way to go around fixing this. Perhaps stashing the cgi.FileStorage instance in the return post dictionary? That would fix the dereference but it's ugly:

diff --git a/bottle.py b/bottle.py
index 9ab7b3d..edae3b5 100644
--- a/bottle.py
+++ b/bottle.py
@@ -1221,6 +1221,7 @@ class BaseRequest(object):
             if item.filename:
                 post[item.name] = FileUpload(item.file, item.name,
                                              item.filename, item.headers)
+                post.__FieldStorage = data
             else:
                 post[item.name] = item.value
         return post

[defnull]

http://bugs.python.org/issue18394 If they do not fix this, we have to. Your workaround looks ok.

[defnull]

Looks like a wont-fix, so we have to.