How to generate temporary file in django and then destroy

Question

I am doing some file processing and for generating the file i need to generate some temporary file from existing data and then use that file as input to my function.

But i am confused where should i save that file and then delete it.

Is there any temp location where files automatically gets deleted after user session

Asked By: Mirage

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Source

Answer 1

You should use something from the tempfile module. I think that it has everything you need.

Answered By: mgilson

Answer 2

Python has the tempfile module for exactly this purpose. You do not need to worry about the location/deletion of the file, it works on all supported platforms.

There are three types of temporary files:

tempfile.TemporaryFile – just basic temporary file,
tempfile.NamedTemporaryFile – "This function operates exactly as TemporaryFile() does, except that the file is guaranteed to have a visible name in the file system (on Unix, the directory entry is not unlinked). That name can be retrieved from the name attribute of the file object.",
tempfile.SpooledTemporaryFile – "This function operates exactly as TemporaryFile() does, except that data is spooled in memory until the file size exceeds max_size, or until the file’s fileno() method is called, at which point the contents are written to disk and operation proceeds as with TemporaryFile().",

EDIT: The example usage you asked for could look like this:

>>> with TemporaryFile() as f:
        f.write('abcdefg')
        f.seek(0)  # go back to the beginning of the file
        print(f.read())

    
abcdefg

Answered By: Tadeck

Answer 3

I just added some important changes: convert str to bytes and a command call to show how external programs can access the file when a path is given.

import os
from tempfile import NamedTemporaryFile
from subprocess import call

with NamedTemporaryFile(mode='w+b') as temp:
    # Encode your text in order to write bytes
    temp.write('abcdefg'.encode())
    # put file buffer to offset=0
    temp.seek(0)

    # use the temp file
    cmd = "cat "+ str(temp.name)
    print(os.system(cmd))

Answered By: alemol

Answer 4

I would add that Django has a built-in NamedTemporaryFile functionality in django.core.files.temp which is recommended for Windows users over using the tempfile module. This is because the Django version utilizes the O_TEMPORARY flag in Windows which prevents the file from being re-opened without the same flag being provided as explained in the code base here.

Using this would look something like:

from django.core.files.temp import NamedTemporaryFile

temp_file = NamedTemporaryFile(delete=True)

Here is a nice little tutorial about it and working with in-memory files, credit to Mayank Jain.

Answered By: Samwise Ganges

How to generate temporary file in django and then destroy

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