I'm working on a Django project (Django 1.10, Python 3.4.3), where I am trying to upload a file in a python subprocess. I need to upload the file and calculate some sums on it as I upload it and we want the system to still be usable while it is doing that, so we thought putting those tasks in a subprocess would work.
Right now, I'm working on just getting the file uploaded.
FIRST ATTEMPT:
app/views/UploadView.py
class NewUploadView(TemplateView):
template_name = "../templates/simulation/upload.html"
@transaction.atomic
def post(self, request):
if request.method == 'POST':
if not request.FILES['input_file']:
return HttpResponseBadRequest("No 'input_file' is provided")
else:
sim_name = self.request.POST.get(u"name", None)
p = Popen(["/.virtualenvs/env/bin/python3.4", "manage.py",
"load_simulation", str(request.FILES['input_file'],
str(sim_name)])
p.communicate()
# Redirect to appropriate page
HttpResponseRedirect(reverse('home.display_simulations'))`
app/management/commands/load_simulation.py
import csv
import os
from django.conf import settings
from django.core.management.base import BaseCommand
from website.apps.home.models import Simulation, Location, Data, SimulationModel
class Command(BaseCommand):
help = 'Upload csv data file and save objects in database'
def add_arguments(self, parser):
parser.add_argument("my_file", type=str)
parser.add_argument("simulation_name", type=str)
def handle(self, *args, **options):
"""
Upload data file
:param args:
:param options:
:return:
"""
my_file = options["my_file"]
simulation_name = options["simulation_name"]
# Save the simulation object, with the data_file
simulation = Simulation.objects.create(name=simulation_name, data_file=my_file)
simulation.save()
filename = os.path.join(settings.MEDIA_ROOT, "simulation_files", simulation.getfilename())
file_obj = open(filename, 'r')
dictreader = csv.DictReader(file_obj)
line = None
for line in dictreader:
location = Location.objects.filter(
department_code=line['department_code'],
municipality_code=line['municipality_code'],
).first()
if not location:
location = Location.objects.create(
department=line['department'],
department_code=line['department_code'],
municipality=line['municipality'],
municipality_code=line['municipality_code'],
)
Data.objects.create(
location=location,
date=line['date'].split(" ")[0], # Assuming date is in "YYYY-MM-DD HH:MM:SS" format
simulation=simulation,
value_low=line['value_low'],
value_mid=line['value_mid'],
value_high=line['value_high'],
)
simulation.is_uploaded = True
simulation.save()
print("DONE WITH LOAD SIMULATION!")
I have it set up so that the file will be saved in the /media/simulation_files directory. But the file wouldn't save to the server, which means it fails in the load_simulation.py file at the line where it tries to open the file since the file isn't at that location.
Then I realized that I'm passing in a TemporaryFile as a string, so maybe that's part of the problem.
SECOND ATTEMPT
I changed part of UploadView.py to take in the file as stdin.
p = Popen(["/.virtualenvs/env/bin/python3.4", "manage.py",
"load_simulation", str(sim_name), is_historical],
stdin=PIPE)
p.communicate(input=request.FILES['output_file'])
and modified load_simulation.py to begin as follows:
class Command(BaseCommand):
help = 'Upload csv data file and save objects in database'
def add_arguments(self, parser):
parser.add_argument("my_file", type=str)
parser.add_argument("simulation_name", type=str)
def handle(self, *args, **options):
"""
Upload data file
:param args:
:param options:
:return:
"""
simulation_name = options["simulation_name"]
my_file = input()
# Save the simulation object, with the data_file
simulation = Simulation.objects.create(name=simulation_name, data_file=my_file.name)
simulation.save()
filename = os.path.join(settings.MEDIA_ROOT, "simulation_files", simulation.getfilename())
file_obj = open(filename, 'r')
dictreader = csv.DictReader(file_obj)
... same as before ...
which I got from the following question/answer: Python3 subprocess communicate example
This gives me an error
TypeError: 'InMemoryUploadedFile' does not support the buffer interface
I'm new to working with subprocesses and am at a loss for what to try next. I do realize that p.communicate() may not be the best choice here, but I'm hoping that will work to get the basic functionality down and then I can improve it. Suggestions and advice are most appreciated!
