I'm trying to submit a form, where the user can potentially upload several files, from which a background process is triggered that will take several minutes to complete. The issue I have currently is that when the user clicks the Submit button, nothing appears to happen for the user for several seconds while the files upload. Is there a way I can redirect to a (static*) holding page while the files upload and the processing happens, and then once the background process completes, this renders a new template?
Using Python 3.6.1 and Flask 0.12.2.
* I say static for now, but at some point in the future, I wish to use AJAX to update this page to give more information to the user
N.B. I have seen several similar questions, and the general answer is to use a module like Celery to perform async operations. Unfortunately, I do not have access to Celery as I cannot download new packages due to corporate policy.
main.py:
from flask import Flask, request, render_template, url_for, redirect
app = Flask(__name__, static_url_path = "/static", static_folder = "static")
@app.route("/", methods=['GET'])
def home():
return render_template("index.html")
@app.route("/in_progress", methods=['GET', 'POST'])
def in_progress():
if request.method == 'GET':
# Do the background processing here
return render_template('result.html') # This is the final part of the process
elif request.method == 'POST':
# Upload the files and do some pre-processing with the form
# This takes a couple of seconds so appears to not be doing anything for the user
# Want to render the GET 'in_progress.html' template at the top of this to give a better user experience
return render_template('in_progress.html') # Reloads same page using GET
index.html:
...some irrelevant HTML
<form action="{{ url_for('in_progress') }}" method="POST" id="form" name="form" enctype="multipart/form-data">
...other irrelevant HTML
