I like Flask Framework For Web Application – Python Programming

I think Flask is an amazing Python framework because it is versatile and flexible. Although there is a drawback to using Flask instead of Django such as with Flask you have to implement many features that would come out of the box with Django. For example, with Django, you get a really good admin panel without any effort, but with Flask you have to write the whole admin panel yourself using Flask Security or Flask Login with Flask Admin — these packages together can help you to be able to code a completed admin panel that allows an administrator to do backend stuff and maintain the web application. With Django, the admin panel that comes out of the box looks very nice. Somehow though, perhaps I could be wrong but I’ve found Django’s admin panel, even with extensive personal customization, a heavy custom Django admin panel is still looking too similar to the one that comes out of the box. With Flask, since you have to code this yourself and depending on how much time and effort you put into the admin panel, it could look completely alien from one programmer’s Flask admin panel to the next.

I have learned Python for a couple of months or so, and I have found Flask is easier to work with than Django — I fondly remembered I started with Django first — and I had a hard time with making Django’s routing of internal paths to the way I like it. With Flask though, it’s simple as:

@app.route('/')
def home_page():
    custom code goes here
    return render_template('index.html', some_variable_to_pass_into_Jinja2_template=whatever)

The piece of code above would render an index.html page for a website using Flask. The decorator @app refers to the Flask app itself, and the route part is where the custom method home_page would render the template’s index.html page — in this case, the forward-slash (‘/’) would be a shortcut to render the index.html page. Now, let’s say you have a contact page where a web visitor could email you or so, how would you route this?

@app.route('/contact')
def contact_page():
    custom code goes here
    return render_template('contact.html', whatever=whatever, blah=blah, contact_form=contact_form)

So, when a visitor goes to ‘yourwebsite.yourdomain-name/contact — Flask would render the contact.html page.

I like how Flask routes internal paths like this because it’s so easy to see what is going on — not like Django’s black box. If you take a look at the custom code immediately after the @app.route, you would right away know that the block of codes belongs to what template’s page of the website.

I have heard a lot of people loved to use Flask for writing RESTful API, and I actually had done this once as a practice exercise. I could definitely see why people love Flask for this very purpose — it’s so easy to just jsonify the data using Flask. Once you have jsonify the data, you can totally choose how you would like to return these data when a request is made to the app using Flask. Nonetheless, recently I have been using Flask to just create small websites — not RESTful API — and this is fresher in my mind than doing RESTful API.

To sum it up, I just scratch the surface of what Flask can do in this blog post. Based on my own experience, I’ve found Flask is easier to work with than Django. Deploying the Flask web app felt easier than Django too. For example, once I’d finished writing a Flask web app, all I had to do was initialize a GitHub repository, commit, and push the web app to GitHub. Afterward, I could use Heroku or PythonAnywhere to host my Flask web app either through the free tier or paid tier. Setting up Flask with Heroku or PythonAnywhere isn’t that hard. The key is to do a double-check of the requirements.txt to make sure all required packages that Flask needs to run your web app are listed in this file. Heroku and PythonAnywhere rely on this file to install necessary third-party Python packages. Once you set up the necessary steps for Heroku or PythonAnywhere, the last thing you only have to do is to pull your app’s source from GitHub onto Heroku or PythonAnywhere. On Heroku’s CLI, you can just do [git push heroku main], and on PythonAnywhere Bash console you can just do [git pull].

Anywho, I just completed coding a Portfolio website using Flask. The main feature of this website is to allow a user to add various project showcases so he or she can show off the projects. The website relies on Bootstrap 5 and custom CSS I’d written — this means the whole website is responsive to various screen sizes, including mobile phones. In desktop mode, the website showcase two projects one at a time through the pagination feature — allowing visitors to flip to more projects by clicking next or back to previous projects. In mobile mode, I used lazy load to load the first few showcase projects’ images — then the rest would be loaded on-demand as the website visitors could forever scroll downward till all projects had been loaded. Check out the finished product on https://pythongenex.pythonanywhere.com/.

How To Make Flask’s Flash Message Appears Only Once After User Is Logged-In!

I have been using Flask to work on a personal website for a couple of days. A small snag got me stumped for a while but I finally figured it out. In Flask, you could use flash to alert signed-in users or visitors about their status on your website such as they’d logged in or whatever… One drawback about Flask’s flash message is that it doesn’t go away unless you refresh the browser. Secondly, in the case of an authenticated user, the flash message indicates he’d logged in could appear again and again every time he or she visited the same page.

To solve the problem of Flask’s flash message isn’t going away, I employed JQuery to make the flash message disappear after nine seconds or so. This is easily done by using JQuery, so I won’t go into the detail of how to do this. What I want to talk about is how to make flash messages only appear once after a user is authenticated and logged in.

First, you need to install Flask-Session. Once you got Flask-Session installed, you need to import like so:

from flask_session import Session
from flask import session

Before you can use Flask-Session, you need to configure it to work with Flask.

# Flask-Session
app.config["SESSION_PERMANENT"] = False
app.config["SESSION_TYPE"] = "filesystem"
app.config['SESSION_USE_SIGNER'] = True
Session(app)

In a login section of your website/web app, you could do something like this after you execute a function or whatever you do to log the user in:

session['user_id'] = current_user.id
session['flash_session_page_visit'] = 'page_visit'
flash(f'{current_user.name} is logged in!', 'login message')

The session[‘user_id’] = current_user.id is a Python line of code in which you want to store a user object’s property — that you called from the database — into a session which you named as user_id. The next trick is to create a new session out of the thin air just for the purpose of using a negation on it later. For this purpose I’d created ‘page_visit’ session which is just a bogus string, and then I stored this inside session’s flash_session_page_visit. The next step is to create a session_manager_func() as follow:

def session_manager_func():
    if current_user.is_authenticated:
        if not session.get('user_id):
            logout_user()
        else:
            if not session.get('flash_session_page_visit'):
                flash(f'User Status:  {current_user.name} is logged in!', 'user authentication status')

Now you can use the method session_manager_func() inside any Flask’s route to display any flash message just once after a user is logged in. This trick works because you use the negation keyword not to turn flash_session_page_visit into false. Since Flask’s session will be true and be available as long the browser isn’t closed, then this trick negates this session as if it isn’t there at all — this makes the flash message won’t appear twice as long as the browser isn’t closed, reopened, and then logged in again.

The current_user is the object got created by Flask-Login package that I imported for my program. Using Flask-Login I’m able to refer to any logged-in user as current_user either inside my Python script or in Flask’s Jinja HTML page. This makes me use my time more efficiently since I don’t really have to query the database for verifying a logged-in user.

Anywho, if you want to try this, don’t forget to implement some sort of Javascript or JQuery to make the flash message goes away for how many seconds you want this to happen, OK? Hopefully, this little trick will be of use for you as it is for me. Thanks for reading.