django: Read UPDATING file PERIODICALLY and SHOW data in form

Question

I am new to python, also celery I started to use today only, I am trying to read an updating file periodically I have used these: Reading from a frequently updated file, Python - Reading from a text file that is being written in Windows and Read from a log file as it's being written using python but they didn't even read file let alone periodically!!

My view is:

def myView(request):
title = 'Algorithms'
if request.method == 'GET':
    template = 'algoInput.html'
    form = AlgoInputForm()
    context = {'title': title, 'form': form}

if request.method == 'POST':
    form = AlgoInputForm(request.POST, request.FILES)
    if form.is_valid():
        task = configAndRun(form.cleaned_data)
        output = readFile.delay('algorithms/out-file.txt')

        template = 'result.html'
        result = AlgoResult(initial={'outputData': output})
        context = {'title': title, 'form': form, 'result': result}

return render(request, template, context)

Above configAndRun method use subprocess to run a long task which create a file, you can imagine it as ping google where all output goes to a file. Next method readFile read that file and display output. Its a celery tasks.py as follows:

from celery import shared_task

@shared_task
def readFile(file):
try:
    file = open(file, "r")
    loglines = follow(file)
    data = []
    for line in loglines:
        data.append(line)
    return data
except Exception as e:
    raise e

def follow(thefile):
    thefile.seek(0,2)
    while True:
        line = thefile.readline()
        if not line:
            time.sleep(0.1)
            continue
        yield line

My form is:

class AlgoInputForm(forms.Form):
    epoch = forms.IntegerField(label='Epoch', help_text='Enter Epoch.')
    learnRate = forms.IntegerField(label='Learning rate(η)', help_text='Enter Epoch.')
    miniBatch = forms.IntegerField(label='Mini-batch size(B)', help_text='Enter Mini-batch size.')
class AlgoResult(forms.Form):
    outputData = forms.CharField(label='Evaluation Results', required=False,widget=forms.Textarea(attrs={'rows': 30, 'cols': 80, 'readonly': 'readonly'}))

my celery.py is:

from __future__ import absolute_import, unicode_literals
import os
from celery import Celery

os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'WebApp.settings')

app = Celery('WebApp')

app.config_from_object('django.conf:settings', namespace='CELERY')

app.autodiscover_tasks()

@app.task(bind=True)
def debug_task(self):
    print('Request: {0!r}'.format(self.request))

When I run this project I get something like 5997dad7-c1b9-4258-8f4d-8e45ebcf1c78 as an output on my AlgoResult form.

Can you please give me directions. A code will be appreciated

score 0 · Answer 1 · answered Sep 23 '17 at 22:30

What you are seeing in your form is actually the celery task_id

You cannot expect static Django form to behave asynchronously and follow up your task execution and update front on its own.

You should have some way of asynchronous update to your frontend by implementing one of the techniques ( WebSockets, long pooling etc.)

django: Read UPDATING file PERIODICALLY and SHOW data in form

1 Answers1