id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
35045	Add a PersistedTemporaryFileUploadHandler for file upload	Adnane Guettaf	nobody	"Using the **PersistedTemporaryFileUploadHandler** upload handler, Django will write the uploaded file to a temporary file stored in your system's temporary directory, as the **TemporaryFileUploadHandler** already do. However, the file this time will not be suppressed after your first read, and will persist until you delete it.

**PersistedTemporaryFileUploadHandler** class  inherit from the **TemporaryFileUploadHandler** class.

=== Use cases

- One use case that I personally faced is having many threads reading from the same uploaded file. When one of the threads reads the file content, the file is automatically deleted, and so became unavailable for the other threads.
- Another use case was find in a [https://stackoverflow.com/questions/11835274/django-control-time-of-temporaryuploadedfile-life/76021825 stack overflow] question, where a user was looking for a way to control the life time of the uploaded file.

=== Implementation

== PersistedTemporaryUploadedFile
{{{
#!python
class PersistedTemporaryUploadedFile(UploadedFile):
    """"""
    A file uploaded to a temporary location (i.e. stream-to-disk).
    The file does not get deleted after a first read from disk
    """"""

    def __init__(self, name, content_type, size, charset, content_type_extra=None):
        _, ext = os.path.splitext(name)
        file = tempfile.NamedTemporaryFile(
            suffix="".upload"" + ext,
            dir=settings.FILE_UPLOAD_TEMP_DIR,
            delete=False,  # forbid the file from being deleted automatically
        )
        super().__init__(file, name, content_type, size, charset, content_type_extra)

    def temporary_file_path(self):
        """"""Return the full path of this file.""""""
        return self.file.name

    def close(self):
        try:
            return self.file.close()
        except FileNotFoundError:
            # The file was moved or deleted before the tempfile could unlink
            # it. Still sets self.file.close_called and calls
            # self.file.file.close() before the exception.
            pass
}}}

== PersistedTemporaryFileUploadHandler
{{{
#!python
class PersistedTemporaryFileUploadHandler(TemporaryFileUploadHandler):
    """"""
    Upload handler that streams data into a temporary file.
    The file does not get deleted after a first read and should
    be closed after use.
    """"""

    def new_file(self, *args, **kwargs):
        """"""
        Create the file object to append to as data is coming in.
        """"""
        super().new_file(*args, **kwargs)
        self.file = PersistedTemporaryUploadedFile(
            self.file_name, self.content_type, 0, self.charset, self.content_type_extra
        )
}}}

The upload handler should after be defined in the ''setting'': **FILE_UPLOAD_HANDLERS** setting: **''django.core.files.uploadhandler.PersistedTemporaryFileUploadHandler''**

=== Tests
{{{
#!python
def test_upload_temporary_file_handler(self):
        with tempfile.NamedTemporaryFile() as temp_file:
            temp_file.write(b""a"")
            temp_file.seek(0)
            response = self.client.post(""/temp_file/"", {""file"": temp_file})
            temp_path = response.json()[""temp_path""]
            # File get deleted after first access
            self.assertIs(os.path.exists(temp_path), False)

def test_upload_persisted_temporary_file_handler(self):
        with tempfile.NamedTemporaryFile() as temp_file:
            temp_file.write(b""a"")
            temp_file.seek(0)
            response = self.client.post(
                ""/temp_file/persisted_file/"", {""file"": temp_file}
            )
            temp_path = response.json()[""temp_path""]
            # File does not get deleted after first access
            self.assertIs(os.path.exists(temp_path), True)
            os.remove(temp_path)
            self.assertIs(os.path.exists(temp_path), False)
}}}

=== N.B

Even thought it may be easy to forbid the temporary file from being deleted, I think it's a necessary feature or class to have withing the framework as it's a behavior that I would naturally consider available in such a great framework. 

"	New feature	closed	File uploads/storage	dev	Normal	wontfix	django, uploadhandler, uploadedfile, core, TempraryFileUploadHandler, PersistedTemporaryFileUploadHandler		Unreviewed	0	0	0	0	0	0