CODEWITHSUNDEEP
pythongoogle-chromecachingflask
Silviu Silviu Silviu
Silviu Silviu Silviu

Reputation: 528

How to prevent cached response (flask server, using chrome)

EDIT: Figured it out, press F12, click network, check "Disable cache".

I have a basic flask server I'm using to learn d3. The problem is that chrome is giving me a cached javascript file I'm working with, example.js.

Request Method:GET Status Code:200 OK (from memory cache)

The server itself is sending a non cached response, I can see this by looking at the response directly via:

/static/example.js

I added this in application.py to prevent caching.

@app.after_request
def add_header(r):
    """
    Add headers to both force latest IE rendering engine or Chrome Frame,
    and also to cache the rendered page for 10 minutes.
    """
    r.headers["Cache-Control"] = "no-cache, no-store, must-revalidate"
    r.headers["Pragma"] = "no-cache"
    r.headers["Expires"] = "0"
    r.headers['Cache-Control'] = 'public, max-age=0'
    return r

Here's the entire code

import os
import re
from flask import Flask, jsonify, render_template, request, url_for
from flask_jsglue import JSGlue

from flask import send_file

# configure application
app = Flask(__name__)
JSGlue(app)

# prevent cached responses
@app.after_request
def add_header(r):
    """
    Add headers to both force latest IE rendering engine or Chrome Frame,
    and also to cache the rendered page for 10 minutes.
    """
    r.headers["Cache-Control"] = "no-cache, no-store, must-revalidate"
    r.headers["Pragma"] = "no-cache"
    r.headers["Expires"] = "0"
    r.headers['Cache-Control'] = 'public, max-age=0'
    return r

@app.route("/<string:filename>")
def main(filename):
    """Render file."""
    return render_template(filename)

@app.route("/favicon.ico")
def favicon():
    filename = 'images/fav.png'
    return send_file(filename, mimetype='image/png')

Thanks for reading.

Upvotes: 8

Views: 13956

Answers (1)

Silviu Silviu Silviu
Silviu Silviu Silviu

Reputation: 528

To prevent cached responses from the browser: - press F12 or right click > inspect - click network tab - check "Disable cache".

To prevent cached responses from the server: add the following definition to application.py:

# prevent cached responses
if app.config["DEBUG"]:
    @app.after_request
    def after_request(response):
        response.headers["Cache-Control"] = "no-cache, no-store, must-revalidate, public, max-age=0"
        response.headers["Expires"] = 0
        response.headers["Pragma"] = "no-cache"
        return response

Upvotes: 18

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