How I Structure My Flask Applications

http://mattupstate.com/python/2013/06/26/how-i-structure-my-flask-applications.html

by llambda • 13 years ago

266 46 13 years ago

mattupstate.com

ninetenel3• 13 years ago

Just use django bro

llambda• 13 years ago

Just use django bro

I would be fascinated to read your rationale for just using Django. Specifically I'm curious what use-cases you see as Django having an advantage in? (Specific examples make for a much more interesting dialogue.) In relation to this, do you think there are contrasting use-cases where Flask might excel as a more suitable option? Personally, I do not favor Flask or Django or <insert web application suite here> exclusively; instead I evaluate a use-case and then determine which tool best fits my needs. However, it would be amazing if you could somehow show that "just use django" is axiomatic to web development in Python...

lelandbatey• 13 years ago

Indeed, I'd be curious as well to hear about why someone should use Django. I initially started using Flask because it is the lightest framework I could find in terms of dependencies, boilerplate, and mental-modeling. Additionally, it had EXCELLENT documentation for everything, from the super newbie (me) to the more seasoned expert.

Since then I've yet to run into a case where I want a lot more than what Flask offers. However, If there's something better that I just don't know about, I'd love to hear about it!

ninetenel3• 13 years ago

I'm curious what use-cases you see as Django having an advantage in?

My primary use case involves having a webapp that actually works

aheilbut• 13 years ago

What about Flask vs. CherryPy?

taude• 13 years ago

Use Django when you're an agency making a finite delivery to a client. :)

Edit: on a serious note, use it when all the dependencies it comes with matches what you exactly need. Once you're down the path of swapping something out, all the third-party apps/packages (one of the key features) become useless. This becomes problematic when you start to use something like MongoDB and end up having to write a lot of code on your own.

fixxer2• 13 years ago

Django is a great framework, but it has always struck me as Python's answer to Ruby-on-Rails. Very structured.

Flask is literally a 5-minute ad hoc content management system with all the power to take on massive tasks. The "micro-framework" label is an understatement.

I also think Armin's style is quite elegant and I've learned a lot more about the language just from reading Flask source.

benhoyt• 13 years ago

How is Flask a "content management system"? I thought it was a fairly small set of utilities for writing web applications, aka a microframework. A CMS is a program/app for publishing and editing web pages or blogs, is it not?

nether• 13 years ago

Switching to Flask from Django was like switching to Slackware from Mandrake (back in the day...). For the first time I was actually learning the system I was using.

mattupstate10• 13 years ago

I hear you there. Flask's code base is really easy to get into if you're curious how things work under the hood.

mattupstate10• 13 years ago

Thanks for the mention! If anyone has further questions I'd be happy to answer them here, or in the comments of the article itself.

peter_l_downs• 13 years ago

Thanks for sharing this, it's always nice to hear how other people are set up. Out of curiosity, how do you serve your static files?

mattupstate10• 13 years ago

With Nginx as a reverse proxy whenever possible.

aidos2• 13 years ago

Enjoyed reading through the approach you take and I'll spend some time reading through the code tomorrow to see how it all fits together. It's surprisingly infrequent that an article pops up describing the thought process behind using a specific structure for your code - thanks for taking the time to write it up.

One thing I've done differently on my last couple of projects is to put the core parts of the app into their own packages at the top level and to make a 'web' package that just contains the web interface and the config. That way I make sure that the core application code isn't bound to the web framework at all. Then within my web blueprints they import the bits of the core library they need to do their work. I can then use the main bit of the library myself without having anything to do with the flask app.

The web app itself is responsible for creating a db connection and then injecting that into the core when needed. I've made a simple gateway class that wraps the db connection and deals with persistence.

The data layer is the bit I'm least happy with. Mostly that's because I went with a nosql solution for the db which ultimately has made the data model more complex than it needs to be. Tomorrow I'm going to experiment with switching to SQLAlchemy again to see how that effects things.

Definitely not saying it's the right way to do things but it's another take on how you can structure things and it's been working really well for me. Feels like you're writing an application first and a website second - which changes how you think about the code.

mattupstate10• 13 years ago

I hear you on the "core" library idea. I have strived for this separation before with varying success. I just did not feel as if I wanted to go that far with this article.

dvanduzer• 13 years ago

Have there been any recent rumblings on #pocoo on extension approval?

It'd be great to see Flask-Security gain more prominence (after you change the default away from plaintext of course :)

mattupstate10• 13 years ago

It's only plaintext by default to get up and running as fast as possible, which is why I wrote the extension in the first place. Armin has, on occasion, expressed interest in improving the extension ecosystem but nothing specific yet.

malbs• 13 years ago

Great article, but the best take away for me.. Alembic, awesome! I'd just started to write something myself (poorly)

mattdeboard4• 13 years ago

A couple other things I'd add to this good article:

- I took a couple of good things from Django's manage.py by using Flask-Script. It looks like [1]

- I'm not sure if there's a better way of doing this, but I really want to be able to swap out configurations based on which environment I'm using. I think I've forced some Django structure onto Flask, but that said, I dynamically load in a `settings` object and use that to configure my `app` object. I use something like [2]. Just looking over it again I think I have some extraneous code in there but I'm tired. It works pretty well, so far.

- Flask-SQLAlchemy has some good stuff too but I'm not entirely sold on using it. I'm using it on one project, but not the other. I don't miss it when I don't have it.

1. https://gist.github.com/mattdeboard/5872584

2. https://gist.github.com/mattdeboard/3cbe5395052128e60328

hartror• 13 years ago

Not sold on using it? What are the reasons?

mattdeboard4• 13 years ago

Well, I just haven't had a TON of use for it yet. I'm a little wary that I'll need to work around leaky abstractions. I'm not poo-pooing it, just ... cynical.

mattupstate10• 13 years ago

Good call on the Flask-Script mention. I will add a note about that.

As far as configuration based on environment goes, I really dislike environment based configuration in my project repository. So I use Flask's instance folder functionality:

http://flask.pocoo.org/docs/config/#instance-folders

This file can be used to configure the app based on its environment wether it be local development or my production environment. The shared factory method attempts to load this file and fails silently if it does not exist.

Regarding your SQLAlchemy comment, well...thats just not really something to add to the article now, is it? ;)

mattdeboard4• 13 years ago

Yeah but how would this solve having identical app installations in dev, prod and staging?

nikon• 13 years ago

This is great. As a recently new Python and Flask user it's good to see how things are done in a nicer way than I have hacked together!

Question: I have a web app built in flask, but I also require a worker process in the background that is actively scraping websites and inserting/ updating data into the DB via the ORM. How would you go about that in the cleanest way?

timmipetit• 13 years ago

You could use Celery: http://www.celeryproject.org/

mattupstate10• 13 years ago

http://flask.pocoo.org/docs/patterns/celery/

canistr• 13 years ago

As a newbie to web frameworks, I found Flask was much easier to deploy and I understood what was happening compared to Django. I also found the documentation and support better than that of Tornado and cherryPy.

teilo• 13 years ago

I like and use Flask, but as to how to structure it, I always end up mirroring a classic Django structure: views, models, forms, utils, static, templates etc. About the only thing missing is urls and admin.

It works, and it's easier for me to organize projects according to a common standard.

mattupstate10• 13 years ago

Flask-Admin (http://flask-admin.readthedocs.org) will cover you on the admin area to a certain degree.

How I Structure My Flask Applications

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