My verdict: Start with Django; use Flask once you hit 10M+ users.
• Django -- Sensible defaults. A plugin for most things you may need. Fairly high learning curve, but worth it. I've heard people at big startups say that they've spent weeks building things with Flask that were either built-in, or came as a pluggable app for Django. Pinterest still uses Django for their middleware, but switched over to Flask for their API .
• Flask -- Low learning curve. Very lightweight. The go-to ORM is SQLAlchemy, which is more fully featured, but has a higher learning curve, and is generally less-liked than the Django ORM. Great for hackathons.
• Pyramid -- Extremely configurable. You get to (have to) make a lot of low-level decisions. Serious lack of sensible defaults. Strong community. The IRC channel is helpful, yet time is spent discussing why Pyramid isn't more popular (lack of sensible defaults).
Exactly. Apart from the tutorial there's not much of "a way" of progressing forward (like "learn this now"). Except South/Migration. Learn this.
There are a lot of resources but it follows the Pareto rule, depending on what you need you may need to go learn Localization/Middleware/Advanced ORM queries/Advanced template tags and filters/Details of Requests and Responses/Advanced forms or models (yeah, Django really doesn't help with CSSing your forms)/etc
They're very similar, so learning South won't be detrimental (and it is useful from the moment you learn it)
I think the most exciting and flexible way to do things these days is with a collection of microservices. You can do feature work independently, test small isolable units of functionality, and achieve scale.That said, we could use cross-cutting libraries to make microservice implementation easier...
Developers tend to get excited building microservices because let's be honest, most of us aren't Ops that have to watch those services 24/7.
During the development of Microservices, everything looks rosy, as things evolved, if the organization does not have the skill-sets and the discipline to maintain these microservices, things fall down pretty quickly.
Take logging as an example, I'm betting that many microservices implementation would find it a wee bit challenging to trace a user transaction end-to-end.
The ecosystem is great, too. django-rest-framework in particular makes us oh-so-happy.
Not to knock flask/Pyramid/everything else. Pick what your team can be most productive wit. I just think there are less reasons than ever to get too caught up in choice of framework. There are so many great options now.
Absolutely. If you already know one and like it, go forth and hack. If you're not sure, or don't like the one you have, there are tons of great options. Not just Flask/Django/Pyramid either. Tornado, Bottle, CherryPy, Falcon, and more all have dedicated users (some more than others).
Re: microservices, I think it's much healthier to frame that debate as a matter of tradeoffs rather than one approach being universally better suited than the other.
Add support for multiple-column primary keys
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NULL fields and Unique keys
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Django has the additional requirement that you think exactly like the designers of the monolithic framework or you will spend a lot of time swimming upstream. Ever tried to integrate Django or Celery into a project whose configuration comes from .ini files or some other method? You end up writing your own configuration layer to get something that Django approves of. Don't even get me started on the ORM -- why does it even exist when we have SQLAlchemy?
In the end, convention over configuration (just put your files in the magic locations, for example) is just another term for developer arrogance: of course my way is natural and everyone will want to think like me! With something like Pyramid I never find myself following a debugger down into the guts to understand why it is or isn't doing something -- I have to do this all the time with Django because some piece of magic isn't working as advertised.
Ultimately, something like Django is concerned with "how can I make it work?" What professional engineers should be concerned with are questions like "what happens when it doesn't work?" and "will someone else be able to understand this?" With Django, what happens when it doesn't work is you find yourself about 13 levels deep in the stack looking at some wrapper class in this giant framework. If you do have to get into a Pyramid component, most of them are actually just individual projects, a single developer can understand the whole thing.
The entire work of engineering is to make it work, without also making it comprehensible to others and easily serviceable -- and do it fast. Picking Django because it makes it easy to start a new project is just satisfying one of those, unless you really understand deeply the bowels of the framework or expect to hire someone who does.
With respect to "Will someone else understand the code" - Having trained few engineers to use Django, the main issue always has been correct decomposition of the entire webapp into different submodules or Django "apps" - If the project has been properly modularized, then it is easy to find problems or add functionality.
In short, imho writing good serviceable code does not depend upon the framework - it depends upon the team :)
This is really the best summary. It comes down to what your individual team can be more productive with. If it's Django, use Django. If it's Flask, use Flask.
> Don't even get me started on the ORM -- why does it even exist when we have SQLAlchemy?
There was a time when I thought much the same. But now I am glad for Django's more simple ORM. I've ended up liking ORMs less and less in general. If I'm going to use one, it's only going to be for the more simple queries. For this kind of case, Django's ORM really shines. Even our less technical staffers can get a copy of the DB and run some business analytics queries themselves.
For anything else, I'd much rather write the SQL myself. It's not difficult, and you are going to do better than the ORM could. Additionally, no ORM is going to have 100% support for every feature Postgres or MySQL offers. For example, we've made great use of Common Table Expressions.
> With Django, what happens when it doesn't work is you find yourself about 13 levels deep in the stack looking at some wrapper class in this giant framework. If you do have to get into a Pyramid component, most of them are actually just individual projects, a single developer can understand the whole thing.
Conversely, having a bunch of projects to track and update means breakages can occur in many different places for any given combination of versions.
In practice, we haven't found Django to be difficult to run. Quite the opposite, really. It's a cohesive unit. If you run into an issue, you are going to find lots of mailing list/bug tracker posts walking you through the solution in most cases.
I'm doing exactly that in my current project. It wasn't so bad, just a couple lines in settings.py. ConfigParser FTW!
> In the end, convention over configuration (just put your files in the magic locations, for example) is just another term for developer arrogance: of course my way is natural and everyone will want to think like me!
I'd argue that Flask or Pyramid encourage a form of that too, just in a different place. Yes the Django devs have decided where you should put many of the things, but if someone new comes to your project already knowing Django they'll know where to look for things, whereas a Flask or Pyramid project may have its own idiosyncratic layout.
* Email backend: https://docs.djangoproject.com/en/dev/topics/email/#defining...
* User model: https://docs.djangoproject.com/en/1.7/topics/auth/customizin...
* Authentication backend: https://docs.djangoproject.com/en/1.7/topics/auth/customizin...
Django makes is very easy to write
* Views which extend from generic CBV and only need you to customize your CBV
* Custom template tags
* Wonderful admin pages: Its amazing what you can do with just Inline, list_display, list_search, list_filter etc. If you are willing to read through a bit of ModelAdmin class, then you will see it has nearly all hook points over ridable, though some it could do with a bit of documentation around ModelAdmin hook points.
When people say that `Django is not known about it's 'overridability'.`, they need to back it up with more data, because that not true at all, at least in 1.7
You need not be afraid to use SQL when you need to do something more advanced. You don't need to feel dirty about it. Postgres in particular can do many more things than any ORM is going to be able to cover 100%. Sometimes you can flat out do something much more efficiently than the ORM can with a simple SQL statement.
If you follow this line of thinking, I'm not sure there's a great reason to bother wedging SQLAlchemy into Django, if I'm just going to end up dropping down into SQL for the more advanced queries.
Of course, portability could be more of a concern if you are writing something that you are going to let customers run on their own hardware/environment. Though even then, I'm not sure I'd want to have to deal with supporting customers using every DB server that Django supports...
For me it was very quick to get started with Django and get things done. Documentation and community support is great, and so for Django related libraries. However I found its templating system getting in my way as compared to Jinja.
Flask again damn easy to start with. However I had to spend time looking for auth frameworks, making it work, and found documentation for flask related libraries not very complete. Some modules seemed to be inactive.
Being able to do dynamic routing (via Traversal) is also cool. I really like being able to attach custom objects/attributes to the request object--that lets me write my own datalayer (without an ORM) and have it shared as a singleton across the lifetime of the request. It's also cool that you can write "views" (aka "controllers") either as flat functions or classes.
I personally don't write much server-side HTML munging anymore so I don't have much to say about Chameleon templates. Last time I used them I found the documentation a little lacking but otherwise it worked well. I still prefer Jade.
For SQL I would do something similar but use (for example) SQLAlchemy Core (not ORM) to do DB-agnostic SQL generation. That would essentially give me a SQL API somewhat similar to pymongo.
Being able to write a single line of SQLAlchemy to build relationships into your models seems way simpler than implementing relationships in a custom data layer.
One of the secret weapons of the Django world is Django REST framework. The built-in API browser alone is pretty amazing.
South is also a pretty darn good migrations system, and is well up there too.
I think I could take or leave the Django admin panel for an established app, but for small apps or just getting started, it's a nice thing to have too.
We don't use Django's templating system.
What does this even mean? It can do a lot for me, therefore it's bad?
We use DRF extensively, but we don't come close to using everything that it can do. We don't tend to use ViewSets or the auto-routing features, but the fact that it can do those things doesn't hurt us.
DRF gets so much attention from such a large community. It's constantly improving to the point where we don't have to worry about it. If you fall victim to NIH Syndrome and roll your own, you have to be proactive about finding and addressing your own issues, as well as keeping up with advancements around the ecosystem.
I'd just rather let the people who focus on DRF handle that, and we'll throw a pull request over the wall if we run into anything that hasn't been addressed.
So yeah, there are efficiency gains from DRF, I agree. But (in my opinion), the gains are far less in architectures with separate applications all using DRF. In that case, something like Flask makes more sense to me, purely for the benefit of debugging, logic clarity, and independence.
I recommend a great talk by Kenneth Reitz on exactly this topic.  (He's given a variation on it multiple times -- just search youtube.)
Django is pretty easy to slim down. Yank the middleware you don't need, stick to what you do. No need for stuff like context processors if you are using DRF. You don't have to use models or the ORM at all if you don't want.
I think the line count would be very similar for many cases. For example, if your flask app needed DB access, you'd end up pulling in and boilerplating an ORM anyway. Ditto for sessions/authentication/etc.
The best way to decide which to use is to take your team and hammer out some quick project using your 2-3 leading framework candidates. Whichever your team is more subjectively happy with is where you should go.
There are other considerations, but so many projects fail to gain traction after taking longer than planned to launch. Team productivity is priority #1 for us, though subjectively we've found it to be very easy to find contractors who can be plugged into a Django project with minimal ramp-up.
The our app is build as an ios, android and webapp on top of this api.
It depends on what you're building. And sometimes this approach is not nice. But it works for our usecase.
In conclusion: sometimes your architecture doesn't need a full-fledged webapp framework.
- Django: a big framework for simple projects. Batteries included (most). Even better if it's a CMS. ORM is fine if you don't do anything complicated.
- Pyramid: much more flexible, more "pick and choose". Also try http://jinja.pocoo.org/
- Flask: if you need to get web requests and do whatever you want with it.
Sometimes I’d even like to access the database from external, possibly non-Python tools, and then Django is out of the question, since it does not define a stable API to its database layer, only its ORM.
Therefore, I go with Flask + SQLAlchemy in these cases.
(One time, for a short-lived project, I chose to ignore that Django does not provide a stable database, and simply let Django create the database and then simply assumed that the database table definitions would not change during the lifetime of the project and accessed it externally via SQL. But this was for a short-lived project which would only run for a few days.)
My gripe with Flask is not itself but the other plugins like flask-security which lacks a lot of documentation.
Flask itself is a delight to use but the only trouble is organizing the code in separate files. I still haven't mastered it, I just import the same file which imports all the modules in all of my flask scripts.